Advancement of the technology has resulted in improvement of our lifestyle and has also changed our attitude. When the human population was low and technology was in its infancy, the various kinds of solid wastes generated due to human activities were easily degraded by decomposers present in nature and it did not create any Significant harmful effect on the environment. In the recent times, however human population has increased tremendously and the technology has become greatly advanced. These two factors have contributed Significantly in the deterioration of our environment due to addition of number of wastes.
(i) Samaira took three different types of solid wastes P,Q, R and buried them under the soil in a pot, as she wanted to study their rate of decomposition. Her findings are shown in the given graph

Select the option that correctly identifies P, Q and R

(ii) Which of the following statements regarding solid wastes is correct?
(a) Change in the packaging technology has resulted in generation of lot of solid wastes.
(b) Dumping of solid wastes could reduce the fertility of the soil leading to reduction in crop yield.
(c) Accumulation of solid waste could cause increased incidents of disease in a locality.
(d) All of these
(iii) Teacher kept few solid wastes in her class as given

She asked students to arrange them in group A (Biodegradable) and group B (Non-biodegradable). Select the student that has grouped the items correctly.

(iv) Select the option that incorrectly matches the type of solid waste and its correct disposal system
(a) Plastic bottle - Send for recycling
(b) Used tea leaves and kitchen waste - Collect in a pit to form compost
(c) Used syringes and needle - Wash and reused
(d) Municipal solid waste and fecal sludge - Buried in low lying areas to level uneven surface of land
(v) Given graph shows time taken by different types of materials to decompose.

Which of the following substances could be anon-biodegradable material?

In any given ecosystem, all living organisms are linked in a systematic chain with respect to their mode of manufacturing food/feeding habits. This sequential interlinking of organisms involving transfer of food energy from producers through a series of organisms with repeated eating and being eaten is called the food chain. A food chain may have 3-4 trophic levels.
(i) Which of the following statements regarding food chain is incorrect?
(a) It is a single straight pathway through which food energy travels in the ecosystem.
(b) It adds adaptability and competitiveness to the organisms.
(c) Presence of isolated food chains adds to instability of the ecosystem.
(d) Food chain binds up inorganic nutrients of the ecosystem.
(ii) Consider the following food chain.
Grass \(\longrightarrow\)A \(\longrightarrow\)Frog \(\longrightarrow\) Snake\(\longrightarrow\)Eagle
Which of the following can be placed at A?

(iii) Select the correct food chain.
(a) Aquatic plants \(\longrightarrow\) Tadpole \(\longrightarrow\)Water beetle\(\longrightarrow\)Pike\(\longrightarrow\)Perch
(b) Grass\(\longrightarrow\)Grasshopper\(\longrightarrow\)Snake\(\longrightarrow\) Frog\(\longrightarrow\) Eagle
(c) Grass\(\longrightarrow\) Rabbit\(\longrightarrow\) Wild cat\(\longrightarrow\) Tiger
(d) Zooplankton \(\longrightarrow\) Phytoplankton \(\longrightarrow\)Small fish\(\longrightarrow\)Fish
(iv) Food chains are sustained by producers and _____________.

(v) Select the incorrect statement.
(a) Food chain may terminate at level of herbivore
(b) Food chain is always straight
(c) Food chain may have 3-5 trophic levels
(d) In a food chain, 80 to 90% of potential energy is lost as heat, at each transfer

Alternatives are always available in nature which results in a sort of interlocking pattern or food web. For instance, if a particular species of producers get destroyed by a disease in an ecosystem, herbivores of that area can feed on other species. Also in a food web, any given species may operate simultaneously at more than one trophic level
(i) Refer to the given food web.

What will be the effect on the food web if population of water fleas get eliminated?
(a) Population of water beetles will increase.
(b) Population of insect larvae will remain unaffected.
(c) Population of small fish will decrease.
(d) Population of frog will increase.
(ii) In the given food web, which organism operates at both primary and tertiary consumer level?

(iii) Refer to the given food web.

Which of the following statement the given food web is correct?
(a) When population of U decreases, population of R ants regarding nd V will increase.
(b) When population of Q decreases, population of R, T and U will increase.
(c) When population of R increases, population of S will increase.
(d) When population of S increases, population of R, T and U will also increase.
(iv) Which of the following statements is correct?
(a) Food webs provide alternative pathways of food availability.
(b) Greater alternatives available in a food web make the ecosystem more stable.
(c) Food webs also help in ecosystem development.
(d) All of these
(v) Food webs make a natural ecosystem ____________ than an man-made ecosystem

Some harmful non-biodegradable chemicals, i.e., pesticides (e.g., DDT) and heavy metals (e.g., mercury, arsenic cadmium, etc.) enter the bodies of organism through the food chain and go on concentrating at each trophic level. This phenomenon is called bio-magnification or biological magnification.
(i) Refer to the given food chain
Phytoplankton \(\longrightarrow\) Zooplankton \(\longrightarrow\)Small fish \(\longrightarrow\) Large fish\(\longrightarrow\)Fish eating birds
If concentration of DDT in small fish is estimated to be 0.5 ppm, then amount of DDT in zooplankton and large fish would respectively be

(ii) Refer to the given table.

According to the given data. The correct order in a food chain will be

(iii) A group of scientists analysed samples of five different animals from a river for possible accumulation of DDT in their body due to bio-magnification. The result obtained is shown in the given graph.
The correct order of the food chain operating in a river is

(iv) Higher amount of DDT disturb calcium metabolism of birds. This results in

(v) When animals are sprayed with poisons, they may die immediately, but their bodies still contain the poison. The poison in their bodies will then be passed on to the animals which eat them. What would be the consequence of a mass poisoning of the rabbit population in a grazing food chain and why?
(a) Plants would die quickly as they are eaten by rabbits
(b) Grasshopper would die quickly as all the animals in the food web would be affected
(c) Western rattlesnakes would quickly become poisoned as they eat rabbits
(d) Hawk would become poisoned as they feed on rabbits

Ozone layer is present in the earth's atmosphere. It is in the form of a protective shield. It contains three oxygen atoms (O₃) which are formed as a consequence of photochemical reactions in the environment. Ozone absorbs harmful ultraviolet radiations of the sun. In this way, it protects all living beings on the earth. The thinning of ozone layer due to various human activities allows more UV radiations to pass through it which leads to harmful effects on man, animals and plants.
(i) Ozone layer is present in which layer of the atmosphere?

(ii) Enhanced UV-radiations would affect humans and other animals causing
(a) skin cancer
(b) blindness and increased chances of cataract in eyes
(c) malfunctioning of the immune system
(d) all of these
(iii) Read the given statements regarding ozone.
I. Ozone hole was first discovered over Montreal in 1976.
II. Ozone is a result of photochemical reactions in which starting molecule is oxygen.
III. Harmful chemicals produce active chlorine in presence of UV radiations, that destroys ozone layers.
IV. Ozone absorbs UV-radiations in the range of 800 - 1100 A.
Select the option that correctly identifies them as true (T) and false (F).

(iv) Which of the following are related to depletion of ozone layer?

(v) Refer to the given events regarding thinning of ozone layer and arrange them in a sequence.
I. Active chlorine is produced in presence of UV radiations.
II. CFCs are released in the air.
III. Ozone layer in the stratosphere become thin.
IV. CFCs enter from troposphere into stratosphere.
V. Use of CFCs in refrigerators and air conditioners as coolants.
VI. Active chlorine destroy ozone by converting it into oxygen.

An insulated copper wire wound on a cylindrical cardboard tube such that its length is greater than its diameter is called a solenoid. When an electric current is passed through the solenoid, it produces a magnetic field around it. The magnetic field produced by a current-carrying solenoid is similar to the magnetic field produced by a bar magnet. The field lines inside the solenoid are in the form of parallel straight lines. The strong magnetic field produced inside a current-carrying solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the solenoid. The strength of magnetic field produced by a current carrying solenoid is directly proportional to the number of turns and strength of current in the solenoid.
(i) The strength of magnetic field inside a long current -carrying straight solenoid is
(a) more at the ends than at the centre
(b) minimum in the middle
(c) same at all points
(d) found to increase from one end to the other.
(ii) The north-south polarities of an electromagnet can be found easily by using

(iii) For a current in a long straight solenoid N-and S-poles are created at the two ends.
Among the following statements, the incorrect statement is
(a) The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid.
(b) The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil.
(c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet.
(d) The N- and S-poles exchange position when the direction of current through the solenoid is reversed.
(iv) A long solenoid carrying a current produces a magnetic field B along its axis. If the current is double and the number of turns per cm is halved, then new value of magnetic field is

(v) A soft iron bar is enclosed by a coil of insulated copper wire as shown in figure. When the plug of the key is closed, the face B of the iron bar marked as

A magnetic field is described by drawing the magnetic field lines. When a small north magnetic pole is placed in the magnetic field created by a magnet, it will experience a force. And if the north pole is free, it will move under the influence of magnetic field. The path traced by a north magnetic pole free to move under the influence of a magnetic field is called a magnetic field line. Since the direction of magnetic field line is the direction of force on a north pole, so the magnetic field lines always begin from the N-pole of a magnet and end on the S-pole of the magnet. Inside the magnet, however the direction of magnetic field lines is from the S-pole of the magnet to the N-pole of the magnet. Thus, the magnetic field lines are closed curves. When a small compass is moved along a magnetic field line, the compass needle always sets itself along the line tangential to it. So, a line drawn from the south pole of the compass needle to its north pole indicates the direction of the magnetic field at that point.

(i) The magnetic field lines
(a) intersect at right angle to one another
(b) intersect at an angle of 45° to each other
(c) do not cross one another
(d) cross at an angle of 60° to one another.
(ii) A strong bar magnet is placed vertically above a horizontal wooden board. The magnetic lines of force will be
(a) only in horizontal plane around the magnet
(b) only in vertical plane around the magnet
(c) in horizontal as well as in vertical planes around the magnet
(d) in all the planes around the magnet.
(iii) Magnetic field lines can be used to determine
(a) the shape of the magnetic field
(b) only the direction of the magnetic field
(c) only the relative strength of the magnetic field
(d) both the direction and the relative strength of the magnetic field.
(iv) The magnetic field lines due to a bar magnet are correctly shown in figure

(v) Which of the following is not true about magnetic field lines?
(a) Magnetic field lines are the closed and continuous curve.
(b) No two field lines can cross each other.
(c) Crowdness of field lines represents the strength of magnetic field.
(d) The direction of field lines is from the north pole to the south pole inside a bar magnet.

Andre Marie Ampere suggested that a magnet must exert an equal and opposite force on a current carrying conductor, which was experimentally found to be true. But we know that current is due to charges in motion. Thus, it is clear that a charge moving in a magnetic field experience a force, except when it is moving in a direction parallel to it. If the direction of motion is perpendicular to the direction of magnetic field, the magnitude of force experienced depends on the charge, velocity (v), strength of magnetic field (B), and sine of the angle between v and B. Direction of magnetic force is given by Fleming's left hand rule.

(i) If an electron is travelling horizontally towards east. A magnetic field in vertically downward direction exerts a force on the electron along

(ii) If a charged particle is moving along a magnetic field line. The magnetic force on the particle is

(iii) A magnetic field exerts no force on
(a) a stationary electric charge
(b) a magnet
(c) an electric charge moving perpendicular to its direction
(d) an unmagnetised iron bar
(iv) A uniform magnetic field exists in the plane of paper pointing from left to right as shown in figure. In the field an electron and a proton move as shown. The electron and the proton experience

(a) forces both pointing into the plane of paper
(b) forces both pointing out of the plane of paper
(c) forces pointing into the plane of paper and out of the plane of paper, respectively
(d) force pointing opposite and along the direction of the uniform magnetic field respectively
(v) An electron beam enters a magnetic field at right angles to it as shown in the figure. The direction of force acting on the electron beam will be

A current carrying wire produces magnetic field around it. The phenomena in which an electromotive force and current (if the conductor is in the form of a closed circuit) is induced by changing magnetic field (or by passing magnetic field lines) through it is called electromagnetic induction. The emf so developed is called induced emf and current made to flow is called induced current. The cause of induced emf carried out by Faraday and Henry. It can be concluded that the induced current flows in a conductor as long as the magnetic lines of force change within the conductor. In case of relative motion i.e., motion of coil w.r.t to magnet or vice versa, the direction of the current flowing in the conductor is determined by the direction of the relative motion of the conductor with respect to the magnetic field. The induced emf or current is directly proportional to the rate of change in magnetic field.

(i) A student connects a coil of wire with a sensitive galvanometer as shown in figure. He will observe the deflection in the galvanometer if bar magnet is

(a) placed near one of the faces of the coil and parallel to the axis of the coil
(b) placed near one of the faces of the coil and perpendicular to the axis of the coil
(c) placed inside the coil
(d) moved towards or away from the coil parallel to the axis of the coil.
(ii) A conducting rod AB moves across two magnets as shown in figure and the needle in the galvanometer deflects momentarily. What is the name of this physical phenomenon?

(iii) A bar magnet is pushed steadily into a long solenoid connected to a sensitive meter.

Which of the following would affect the magnitude of the deflection of the meter?
(a) How fast the magnet is pushed into the coil.
(b) The direction in which the coil is wound.
(c) The end of the solenoid the magnet enters.
(d) The pole of the magnet enters the coil first.
(iv) What is the condition of an electromagnetic induction?
(a) There must be a relative motion between galvanometer and coil of wire.
(b) There must be a relative motion between galvanometer and a magnet.
(c) There must be a relative motion between galvanometer and electric motor.
(d) There must be a relative motion between the coil of wire and a magnet.
(v) An induced emf is produced when a magnet is plunged into a coil. The magnitude of induced emf does not depend on

An electric motor is a rotating device that converts electrical energy into mechanical energy. Electric motor is used as an important component in electric fans, refrigerators, mixers, washing machines, computers, MP3 players, etc.

An electric motor consists of a rectangular coil ABCD of insulated copper wire. The coil is placed between the two poles of a magnetic field such that the arm AB and CD are perpendicular to the direction of the magnetic field. The ends of the coil are connected to the two halves P and Q of a split ring. The inner sides of these halves are insulated and attached to an axle. The external conducting edges of P and Q touch two conducting stationary brushes X and Y respectively, as shown in the figure. Commercial motors use an electromagnet in place of a permanent magnet, a large number of turns of conducting wire in the current carrying coil and a soft iron core on which the coil is wound.
(i) Choose incorrect statement from the following regarding split rings.
(a) Split rings are used to reverse the direction of current in coil.
(b) Split rings are also known as commutator.
(c) Split ring ii a discontinuous or a broken ring.
(d) Both (a) and (b)
(ii) Which of the following has no effect on the size of the turning effect on the coil of an electric motor?

(iii) When current is switched ON, an electric fan converts

(iv) In an electric motor, device that makes contact with the rotating rings and through them to supply current to coil is

(v) In an electric motor, the direction of current in the coil changes once in each

The rate of flow of charge is called electric current. The SI unit of electric current is Ampere (A). The direction of flow of current is always opposite to the direction of flow of electrons in the current.
The electric potential is defined as the amount of work done in bringing a unit positive test charge from infinity to a point in the electric field. The amount of work done in bringing a unit positive test charge from one point to another point in an electric field is defined as potential difference.
\(\begin{equation} V_{A B}=V_{B}-V_{A}=\frac{W_{B A}}{q} \end{equation}\)
The SI unit of potential and potential difference is volt.
(i) The 2 C of charge is flowing through a conductor in 100 rns, the current in the circuit is

(ii) Which of the following is true?
(a) Current flows from positive terminal of the cell to the negative terminal of the cell outside the cell.
(b) The negative charge moves from lower potential to higher potential.
(c) The direction of flow of current in same as the direction of flow of positive charge.
(d) All of these
(iii) The potential difference between the two terminals of a battery, if 100 joules of work is required to transfer 20 coulombs of charge from one terminal of the battery to other is

(iv) The number of electrons flowing per second in a conductor if 1A current is passing through it

(v) The voltage can be written as

The relationship between potential difference and current was first established by George Simon Ohm called Ohm's law. According to this law, the current through a metallic conductor is proportional to the potential difference applied between its ends, provided the temperature remain constant i.e. I \(\begin{equation} \propto \end{equation}\) V or V = IR; where R is constant for the conductor and it is called resistance of the conductor. Although Ohm's law has been found valid over a large class of materials, there do exist materials and devices used in electric circuits where the proportionality of V and I does not hold.
(i) If both the potential difference and the resistance in a circuit are doubled, then

(ii) For a conductor, the graph between V and I is there. Which one is the correct?

(a)	(b)
(c)	(d)

(iii) The slope of V - I graph (V on x-axis and I on y-axis) gives

(iv) When battery of 9 V is connected across a conductor and the current flows is 0.1 A, the resistance is

(v) By increasing the voltage across a conductor, the

The obstruction offered by a conductor in the path of flow of current is called resistance. The SI unit of resistance is ohm (\(\begin{equation} \Omega \end{equation}\)). It has been found that the resistance of a conductor depends on the temperature of the conductor. As the temperature increases the resistance also increases. But the resistance of alloys like mangnin, constantan and nichrome is almost unaffected by temperature. The resistance of a conductor also depends on the length of conductor and the area of cross-section of the conductor. More be the length, more will be the resistance, more be the area of cross-section, lesser will be the resistance.
(i) Which of the following is not will desired in material being used for making electrical wires?

(ii) The V - I graph for two metallic wires A and B is given. What is the correct relationship between their temperatures?

(iii) Two wires of same material one of length L and area of cross-section A, other is of length 2L and area A/2 . Which of the following is correct?

(iv) For the same conducting wire
(a) resistance is higher in summer
(b) resistance is higher in winter
(c) resistance is same is summer or in winter
(d) none of these
(v) A wire of resistance 20 \(\begin{equation} \Omega \end{equation}\)  is cut into 5 equal pieces. The resistance of each part is

Two or more resistances are connected in series or in parallel or both, depending upon whether we want to increase or decrease the circuit resistance.

The two or more resistances are said to be connected in series if the current flowing through each resistor is same. The equivalent resistance in the series combination is given by 
R_s = R₁ + R₂ + R₃
(i) When three resistors are connected in series with a battery of voltage V and voltage drop across resistors is V₁, V₂ and V₃, which of the relation is correct?

(ii) When the three resistors each of resistance R ohm, connected in series, the equivalent resistance is

 (iii) There is a wire oflength 20 cm and having resistance 20 \(\begin{equation} \Omega \end{equation}\) cut into 4 equal pieces and then joined in series.
The equivalent resistance is

(iv) In the following circuit, find the equivalent resistance between A and B is (R = 2 \(\begin{equation} \Omega \end{equation}\))

(v) In the given circuit, the current in each resistor is

If two or more resistances are connected in such a way that the same potential difference gets applied to each of them, then they are said to be connected in parallel. The. current flowing through the two resistances in parallel is, however, not the same. When we have two or more resistances joined in parallel to one another, then the same current gets additional paths to flow and the overall resistance decreases. The equivalent resistance is given by \(\begin{equation} \frac{1}{R_{p}}=\frac{1}{R_{1}}+\frac{1}{R_{2}}+\frac{1}{R_{3}} \end{equation}\)

(i) Three resistances, 2 \(\begin{equation} \Omega \end{equation}\) , 6 \(\begin{equation} \Omega \end{equation}\) and 8 \(\begin{equation} \Omega \end{equation}\) are connected in parallel, then the equivalent resistance is
(a) less than 6 \(\begin{equation} \Omega \end{equation}\) but more than 2 \(\begin{equation} \Omega \end{equation}\)
(b) less than 8 \(\begin{equation} \Omega \end{equation}\) but more than 6 \(\begin{equation} \Omega \end{equation}\)
(c) less than 2 \(\begin{equation} \Omega \end{equation}\)
(d) more than 8 \(\begin{equation} \Omega \end{equation}\)
(ii) A wire of resistance 12 \(\begin{equation} \Omega \end{equation}\) is cut into three equal pieces and then twisted their ends together, the equivalent resistance is

(iii) Three resistances are connected as shown. The equivalent resistance between A and B is

(iv) Which of the following relation is correct?

(v) Find the current in each resistance.

A prism is a transparent refracting medium bounded by two plane surfaces inclined to each other at a certain angle. The refraction of light through a prism follows the laws of refraction. In the prism, refraction takes place on its refracting surface it means when the light enters the prism and when the light leaves the prism. The refraction through a prism is shown. Here, A is the angle of prism, \(\angle\)i is the angle of incidence of the face AB and \(\angle\)e is the angle of emergence at other face AC.

The incident ray suffers a deviation or bending through an angle \(\begin{equation} \delta \end{equation}\)  due to the refraction through prism. This angle is called angle of deviation as shown in figure.
\(\angle\)i + \(\angle\)e = \(\angle\)\(\begin{equation} \delta \end{equation}\) + \(\angle\)A
(i) The angle between the two refracting surfaces of a prism is called

(ii) The angle between the incident ray and the emergent ray is called

(iii) When a ray is refracted through a prism, then

(iv) The angle of deviation depends on

(v) The rectangular surfaces of a prism are known as

When white light is incident on one refracting surface of the prism, the light splits up into constituent colours violet, indigo, blue, green, yellow, orange and red. The process of splitting of white light into its seven constituent colours is called dispersion. When the dispersed white light is made to fall on a screen, we get the band of seven colours is called the spectrum of white light. Red colour bends the least on passing through the prism and violet colour bends through maximum angle on passing through the prism.

(i) The splitting of white light can be done by

(ii) Which property of light is used by prism to form a spectrum?

(iii) Which of the following dispersion is correct?

(a)	(b)
(c)	(d)

(iv) When a red light passes through a prism, it
(a) will not split
(b) will split into seven colours
(c) will split into white colour
(d) will split into many different colours.
(v) The spectrum produced by the white light by a prism is called

Light of all the colour travel at the same speed in vacuum for all wavelengths. But in any transparent medium
(glass or water), the light of different colours travel with different speeds for different wavelength that means
that the refractive index of a particular medium is different for different wavelength. As there is a difference in
their speeds, the light of different colour bend through different angles. The speed of violet colour is maximum and the speed of red colour is minimum in glass so, the red light deviates least and violet colour deviates most.
Hence, higher the wavelength of a colour of light, smaller the refractive index and less is the bending of light.
\(\begin{equation} \lambda \end{equation}\)r > \(\begin{equation} \lambda \end{equation}\)v and r_n < v_n, \(\begin{equation} v=\frac{c}{\lambda} . \end{equation}\)
(i) Which of the following statements is correct regarding the propagation of light of different colours of white light in air?
(a) Red light moves fastest.
(b) Blue light moves faster than green light.
(c) All the colours of the white light move with the same speed.
(d) Yellow light moves with the mean speed as that of the red and the violet light.
(ii) Which of the following is the correct order of wavelength?

(iii) Which of the following is the correct order of speed of light in glass?

(iv) Which colour which has maximum frequency

(v) Which of the following is the correct order of angle of deviation?

The spreading of light by the air molecules is called scattering of light. The light having least wavelength scatters more. The sun appears red at sunrise and sunset, appearance of blue sky it is due to the scattering of light. The colour of the scattered light depends on the size of particles. The smaller the molecules in the atmosphere scatter smaller wavelengths of light. The amount of scattering of light depends on the wavelength of light. When light from sun enters the earth's atmosphere, it gets scattered by the dust particles and air molecules present in the atmosphere. The path of sunlight entering in the dark room through a fine hole is seen because of scattering of the sun light by the dust particles present in its path inside the room.
(i) To an astronaut in a spaceship, the colour of earth appears

(ii) At the time of sunrise and sunset, the light from sun has to travel.
(a) longest distance of atmosphere
(b) shortest distance of atmosphere
(c) both (a) and (b)
(d) can't say
(iii) The colour of sky appears blue, it is due to the
(a) refraction oflight through the atmosphere
(b) dispersion of light by air molecules
(c) scattering of light by air molecules
(d) all of these.
(iv) At the time of sunrise and sunset
(a) Blue colour scattered and red colour reaches our eye
(b) Red colour scattered and blue colour reaches our eye
(c) Green and blue scattered and orange reaches our eye
(d) None of these
(v) The danger signs made red in colour, because
(a) the red light can be seen from farthest distance
(b) the scattering of red light is least
(c) both (a) and (b)
(d) none of these

Atmospheric refraction is the phenomenon of bending of light on passing through earth's atmosphere. As we move above the surface of earth, density of air goes on decreasing. Local conditions like temperature etc. also affect the optical density of earth's atmosphere. On account of atmospheric refraction, stars seen appear higher than they actual are; advanced sunrise; delayed sunset, oval appearance of the sun at sunrise and sunset; stars twinkle, planets do not.
(i) Due to atmospheric refraction, apparent length of the day

(ii) Apparent position of the star appears raised due to

(iii) The sun appears oval shaped or flattened due to

(iv) Twinkling of stars and non-twinkling of planets is accounted for by

(v) In absence of atmosphere, the colour of sky appears

The curved surface of a spoon can be considered as a spherical mirror. A highly smooth polished surface is called mirror. The mirror whose reflecting surface is curved inwards or outwards is called a spherical mirror. Inner part works as a concave mirror and the outer bulging part acts as a convex mirror. The center of the reflecting surface of a mirror is called pole and the radius of the sphere of which the mirror is formed is called radius of curvature.
(i) When a concave mirror is held towards the sun and its sharp image is formed on a piece of carbon paper for some time, a hole is burnt in the carbon paper. What is the name given to the distance between the mirror and carbon paper?

(ii) The distance between pole and focal point of a spherical mirror is equal to the distance between

(iii) The focal length of a mirror is 15 cm. The radius of curvature is

(iv) The normal at any point on the mirror passes through

(v) In a convex spherical mirror, reflection of light takes place at

The spherical mirror forms different types of images when the object is placed at different locations.
When the image is formed on screen, the image is real and when the image does not form on screen, the image is virtual. When the two reflected rays meet actually, the image is real and when they appear to meet, the image is virtual.
A concave mirror always forms a real and inverted image for different positions of the object. But if the object is placed between the focus and pole, the image formed is virtual and erect.
A convex mirror always forms a virtual, erect and diminished image. A concave mirror is used as doctor's head mirror to focus light on body parts like eyes, ears, nose etc., to be examined because it can form erect and magnified image of the object. The convex mirror is used as a rear view mirrors in automobiles because it can form an small and erect image of an object.
(i) When an object is placed at the centre of curvature of a concave mirror, the image formed is

(ii) No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be

(iii) A child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size and that of the legs smaller. The following is the order of combinations for the magic mirror from the top.

(iv) To get an image larger than the object, one can use
(a) convex mirror but not a concave mirror
(b) a concave mirror but not a convex mirror
(c) either a convex mirror or a concave mirror
(d) a plane mirror.
(v) A convex mirror has wider field of view because
(a) the image formed is much smaller than the object and large number of images can be seen
(b) the image formed is much closer to the mirror
(c) both (a) and (b)
(d) none of these.

The relation between distance of an object from the mirror (u), distance of image from the mirror (v) and the focal length (F) is called mirror formula. This formula is valid in all situations for all spherical mirrors for all positions of the object. The size of image formed by a spherical mirror depends on the position of the object from the mirror. The image formed by a spherical mirror can be bigger than the object, equal to the object or smaller than the object. The size of the image relative to the object is given by the linear magnification (m). Thus, the magnification is given by the ratio of height of image to the height of object. If magnification is negative, image is real and if it is positive, image is virtual.
(i) What is the position of an image when an object is placed at a distance of 20 em from a concave mirror of
focal length 20 cm?

(ii) Which of the following ray diagrams is correct for the ray of light incident on a concave mirror as shown in figure?

(a) Figure A	(b) Figure B
(C) Figure C	(d) Figure D

(iii) If the magnification of an image is -2, the characteristic of image will be

(iv) The mirror formula holds for

(v) A parallel beam of light is made to fall on a concave mirror. An image is formed at a distance of7.5 from the mirror. The focal length of the mirror is

When the rays of light travels from one transparent medium to another, the path of light is deviated. This phenomena is called refraction of light. The bending of light depends on the optical density of medium through which the light pass.

The speed of light varies from medium to medium. A medium in which the speed of light is more is optically rarer medium whereas in which the speed of light is less is optically denser medium. Whenever light goes from one medium to another, the frequency of light does not change however, speed and wavelength change. It concluded that change in speed of light is the basic cause of refraction.
(i) When light travels from air to glass, the ray of light bends

(ii) A ray of light passes from a medium A to another medium B. No bending of light occurs if the ray of light hits the boundary of medium B at an angle of

(iii) When light passes from one medium to another, the frequency of light

(iv) When light passes from glass to water, the speed of light

(v) The bottom of pool filled with water appears to be ______ due to refraction of light

The refraction of light on going from one medium to another takes place according to two laws which are known as the laws of refraction of light. These laws are
1. The ratio of sine of angle of incidence to the sine of angle of refraction is always constant for the pair of media in contact.
\(\frac{\sin i}{\sin r}=\mu=\text { constant }\)
This constant is called refractive index of the second medium with respect to the first medium.
Refractive index is also defined as the ratio of speed of light in vacuum to the speed of light in medium.
2. The incident ray, refracted ray and normal all lie in the same plane.
This law is called Snell's law of refraction.
(i) When light travels from air to glass,
(a) angle of incidence > angle of refraction
(b) angle of incidence < angle of refraction
(c) angle of incidence = angle of refraction
(d) can't say
(ii) When light travels from air to medium, the angle of incidence is 45° and angle of refraction is 30°. The refractive index of second medium with respect to the first medium is 

(iii) In which medium, the speed of light is minimum?

(iv) If the refractive index of glass is 1.5 and speed of light in air is 3 x 10⁸ m/s. The speed of light in glass is

(v) Refractive index of a with respect to b is 2. Find the refractive index of b with respect to a.

Sex determination is the method by which distinction between males and females is established in a species. The sex of an individual is determined by specific chromosomes. These chromosomes are called sex chromosomes or allosomes. X and Y chromosomes are called sex chromosomes. The normal chromosomes other than the sex chromosomes of an individual are known as autosomes.
(i) In XX-XO type of sex determination
(a) females produce two different types of gametes
(b) males produce two different types of gametes
(c) females produce gametes with Y chromosome
(d) males produce gametes with Y chromosome.
(ii) A couple has six daughters. What is the possibility of their having a girl next time?

(iii) Number of autosomes present in liver cells of a human female is

(iv) XX-XO type of sex determination and XX-XY type of sex determination are the examples of

(v) Select the incorrect statement.
(a) In male grasshoppers, 50% of sperms have no sex chromosome
(b) Female fruitfly is heterogametic
(c) Human male produces two types of sperms 50% having X chromosome and 50% having Y chromosomes
(d) In turtle, sex determination is regulated by environmental factors.

Gregor Mendel conducted hybridisation experiments on garden peas for seven years and proposed the laws of inheritance in living organisms. He investigated characters in the garden pea plant that were manifested as two opposing traits, e.g., tall or dwarf plants, yellow and green seeds, etc.
(i) Among the seven pairs of contrasting traits in pea plant as studied by Mendel, the number of traits related
to flower, pod and seed respectively were

(ii) The colour based contrasting traits in seven contrasting pairs, studied by Mendel in pea plant were

(iii) Refer to the given table of contrasting traits in pea plants studied by Mendel.

Character	Dominant trait	Recessive trait
(i) Seed colour
(ii) Flower colour
(iii) Pod shape
(iv) Flower position

Which of the given traits is correctly placed?
(a) (i), (ii) and (iii) only
(b) (ii), (iii) and (iv) only
(c) (ii) and (iii) only
(d) (i), (ii), (iii) and (iv)
(iv) Some of the dominant traits studied by Mendel were
(a) round seed shape, green seed colour and axial flower position
(b) terminal flower position, green pod colour and inflated pod shape
(c) violet flower colour, green pod colour and round seed shape
(d) wrinkled seed shape, yellow pod colour and axial flower position.
(v) Which of the following characters was not chosen by Mendel?

Mendel crossed tall and dwarf pea plants to study the inheritance of one gene. He collected the seeds produced as a result of this cross and grew them to generate plants of the first hybrid generation which is called the first filial progeny or F₁: Mendel then self pollinated the tall F₁ plants and he obtained F₂ generation.
(i) In garden pea, round shape of seeds is dominant over wrinkled shape. A pea plant heterozygous for round shape of seed is selfed and 1600 seeds produced during the cross are subsequently germinated. How many seedlings would have non-parental phenotype?

(ii) If 'A' represents the dominant gene and 'a' represents its recessive allele, which of the following would be the most likely result in the first generation offspring when Aa is crossed with aa ?
(a) All will exhibit dominant phenotype.
(b) All will exhibit recessive phenotype.
(c) Dominant and recessive phenotypes will be 50% each.
(d) Dominant phenotype will be 75%.
(iii) Which of the following crosses will give tall and dwarf pea plants in same proportions?

A)	B)
c)	D)

(iv) What result Mendel would have got, if he self pollinated a homozygous tall F₂ plant?
(a) TT and Tt
(b) All Tt
(c) All TT
(d) All tt
(v) In plant, tall phenotype is dominant over dwarf phenotype, and the alleles are designated as T and t, respectively. Upon crossing one tall and one dwarf plant, total 250 plants were obtained, out of which 124 displayed tall phenotype and rest were dwarf. Thus, the genotype of the parent plants were
(a) TT x TT
(b) TT x tt
(c) Tt x Tt
d) Tt x tt.

The cross that include the inheritance of two pairs of contrasting characters simultaneously is referred as dihybrid cross. Mendel chose pure breeding plants for yellow and green seeds and round and wrinkled shape of seeds. He cross pollinated the plant having yellow round seeds with plant having green wrinkled seeds. All the plants produced in F₁ generation were having, yellow round seeds. The plants raised from these seeds were self pollinated, that resulted in production of plants having four phenotypically different types of seeds.
(i) When a cross is made between a yellow round seeded plant (YyRr) and a yellow wrinkled seeded plant (Yyrr), what is true regarding the proportions of phenotypes of the offsprings in F₁ generation?

(ii) How many types of gametes can be produced by YYrr?

(iii) In Mendelian dihybrid cross, when heterozygous tall plant with green seeds are self crossed the progenies are

(iv) When round yellow seeded heterozygous pea plants are self fertilised, the frequency of occurrence of RrYY genotype among the offsprings is

(v) The percentage of yr gamete produced by YyRr parent will be

In human, the allele for brown eyes (B) is dominant over that for blue eyes (b). A brown eyed woman marries a blue eyed man, and they have six children. Four of the children are brown eyed and two of them are blue eyed.
(i) What is the genotype of blue eyed offspring?

(ii) What is the woman's genotype?

(iii) The ovum, produced by the mother carries the gene regarding eye colour is

(iv) The ratio of brown eyed children to blue eyed children in this family is 2 : 1, which deviates from typical phenotypic ratios for monohybrid inheritance. What might be the reason?
(a) Gametes carrying the brown eyed allele are more viable then those with the blue eyed allele.
(b) A different pattern of inheritance other than monohybrid inheritance is involved.
(c) Not all of their babies survived childbirth, thus causing a distortion in the actual ratio.
(d) The actual ratio differs from the expected ratio because the sample size is too small.
(v) What is the gene carried by of the man's sperm regarding the eye colour?

There are two organisms X and Y that produce new offspring from single parent only.Organisms X when reaches its maximum growth, divides its body into two new organisms.
The parent organism does not exist any more and two new daughter organisms grow fully and divide again. Organism Y form a small outgrowth on its body called bud which detaches and develops into new organism .
Read the above paragraph and answer the questions that follow.
(I) Select the option that correctly identifies organisms X and Y.

(ii) Select the correct statement.
(a) Organism X reproduces asexually whereas organism Y reproduces sexually
(b) Organism X must be multicellular whereas organism Y should be unicellular
(c) Both organisms X and Y reproduce asexually
(d) Both organisms X and Yare always multicellular organisms
(iii) Identify the mode of reproduction in organisms X and Y.

(iv) Which of the following is incorrect?
(a) Plasmodium reproduces by the same method as is adopted by organism X.
(b) Organism X could be any multicellular plant like Riccia, Sphagnum, etc.
(c) If organism Y is Hydra, then it may also reproduce through regeneration.
(d) Both (a) and (b)
(v) Which organism reproduces by the method shown in the given figure?

Spore formation, method of asexual reproduction is used by unicellular as well as multicellular organisms.Spores are microscopic units which could be air borne or are present in soil, etc.
(i) A slice of bread kept in open for sometime shows growing white cottony mass which later turns black. This happens because
(a) bacterial spores present in air germinate on the surface of bread slice
(b) fungal spores present in air germinate on the surface of bread slice
(c) protozoan microbes start feeding on bread slice
(d) none ef these.
(ii) Spore formation can be seen in

(iii) Bulb like structure at top of erect hyphae where spores are produced is

(iv) Select the incorrect statement.
(a) Spores can be produced endogenously or exogenously in an organism.
(b) Spores can be air borne or soil borne.
(c) Bacteria produce only exospores.
(d) Rhizopus bears spores in special structures called sporangium.
(v) Observe the given figure showing spores formation in Rhizopus and select the option which is correctly labelled.

(a) P-Stolon, S-Columella, T-Sporangiophore
(b) Q-Stolon, P-Hypha, S-Sporangium
(c) R-Sporangium, S-Apophysis, T-Sporangiophore
(d) Q-Stolon, R-Sporangium, S-Colume!la

Radhika collected some pond water which was dark green in colour in a test tube. She took out green coloured mass from it and separated its filaments by using needles. She broke some filaments into small fragments and put them in a Petri dish containing clean water. She observed that after few days the small fragments gave rise to complete filaments.
(i) What do you think the mass of green filament was?
(a) It was a mass of Spirogyra filament
(b) It was a colony of Volvox algae
(c) It was kelp, i.e., large brown algae
(d) It was a mass of fungal filaments or hyphae.
(ii) The small fragment gave rise to new filament. What does it indicate?
(a) Spirogyra reproduces asexually through fragmentation
(b) Spirogyra reproduces asexually through vegetative propagation
(c) Spirogyra reproduces asexually through budding
(d) Spirogyra reproduces asexually through fission
(iii) Organism which reproduces in similar way as Spirogyra is

(iv) Select the correct statement.
(a) Only multicellular organisms can undergo fragmentation
(b) Both unicellular and multicellular organisms can undergo fragmentation
(c) Fragmentation is sexual mode of reproduction
(d) Fragmentation is found only in algae.
(v) Which among the given organisms do not reproduce by fragmentation?

Preeti is very fond of gardening. She has different flowering plants in her garden. One day few naughty children entered her garden and plucked many leaves of Bryophyllum plant and threw them here and there in the garden. After few days, Preeti observed that new Bryophyllum plants were coming out from the leaves which fell on the ground.
(i) What does the incidence cited in the paragraph indicate?
(a) Bryophyllum leaves have special buds that germinate to give rise to new plant
(b) Bryophyllum can propagate vegetatively through leaves
(c) Bryophyllum is a flowering plant that reproduces only asexually
(d) Both (a) and (b)
(ii) Which of the following plants can propagate vegetatively through leaves like Bryophyllum?

(iii) Do you think any other vegetative part of Bryophyllum can help in propagation? If yes, then which part?

(iv) Which of the following plants is artificially propagated (vegetatively) by stem cuttings in horticultural practices?

(v) In which of the following pairs both the plants can be vegetatively propagated by leaf pieces?

Horticultural methods of vegetative propagation multiply desired varieties of plants quickly from parts of their somatic body. A horticulturist used stem cutting of plant X to propagate it in a short span of time. For plant Y, he pulled a branch of towards ground and covered it with soil leaving the tip of branch exposed. He later on cut the branch from parent plant. The former developed into new plant. He propagated plant Z through underground stems called tubers. Identify the propagation methods used by horticulturist and answer the following questions.
(i) What could be plants X, Y and Z?

(ii) Select the propagation methods in plants X, Y and Z.
(a) X - root tubers, Y - stem cutting, Z - stem tubers
(b) X - stem cutting, Y - layering, Z - underground stem
(c) X -Iayering, Y - underground stem, Z - underground roots
(d) X - grafting, Y - layering, Z - root tubers
(iii) Select the correct statement for plant Z if it is potato.
(a) Each tuber has many buds called ears
(b) It is necessary to plant the whole potato tuber in the soil to produce new potato plants
(c) Vegetative propagation of potato plants by tubers is much faster than production of potatoes by seeds
(d) All of these.
(iv) Select the plant which propagates by the same method adopted by gardener for plant Y, but naturally it propagates by stolons

(v) Identify the given vegetative propagule.

The small intestine is the longest part of the alimentary canal. It is a narrow tube of about 6 metres which lies coiled in the abdomen. The length of small intestine varies in different animals depending on the type of food they eat.
(i) Humans are not able to digest cellulose whereas they are able to digest starch due to

(ii) What will happen if the lining X shown in the figure of transverse section of gut is smooth instead of having such foldings?

(iii) Butter cannot be digested in the stomach as lipase and bile are(a) released in small intestine

(iv) Which of the following is a correct statement?
(a) Herbivores have shorter small intestine as they eat grasses
(b) Carnivores have larger small intestine as they eat meat
(c) Herbivores have larger small intestine as they eat grasses
(d) None of these
(v) Various types of movements are generated by the ______ layer of the small intestine.

Water is very important chemical, required as solvent, in many biological processes. It is needed as raw material in photosynthesis, as a main substance from which plants evolve oxygen and provide hydrogen for the synthesis of carbohydrates. It helps in translocation of chemical substances and minerals and in this manner maintains internal transportation. Osmosis is a special type of transport of water molecules that occurs through semipermeable membrane. Osmosis is movement of solvent from the region of higher diffusion pressure to the lower diffusion pressure across a semipermeable membrane. It is of two types - endosmosis and exosmosis. Endosmosis is the osmotic entry of water into a cell, organ or system. Exosmosis is the osmotic withdrawal of water from a cell, organ or system.
(i) A flowering plant is planted in an earthen pot and irrigated. Urea is added in high amounts to make the plant grow faster, but after sometime the plant died. This may be due to

(ii) A slice of sugar beet placed in concentrated salt solution would
(a) show no change
(b) loose water and become flaccid initially
(c) absorb small quantity of water
(d) become swollen
(iii) The process of diffusion is involved in

(iv) The plant cell cytoplasm is surrounded by both cell wall and cell membrane. The specificity of transport of substances is mostly across the cell membrane, because
(a) cell membrane is impermeable
(b) cell membrane is selectively permeable
(c) cell membrane is fully permeable
(d) cell wall is impermeable.
(v) Based on the given figure which of the following statements is incorrect?

(a) Movement of solvent molecules will take place from chamber A to B.
(b) Movement of solute will take place from A to B.
(c) Presence of a semi-permeable membrane is a prerequisite for this process to occur.
(d) The direction and rate of osmosis depends on both the pressure gradient and concentration gradient

Given are the sections of two pipes, A and B. If you need to represent blood vessels with these, which of the pipes would correspond to the artery and which one to a vein. Identify it and answer the following questions.

(i) B is best defined as the vessel which
(a) always supply oxygenated blood to the different organs
(b) always carry blood away from the heart to different organs
(c) always break up into capillaries that reunite to form a vein
(d) always carry blood from one visceral organ to another visceral organ.
(ii) In A, valves are present to check backward flow of blood flowing at

(iii) Which of the following statements is correct regarding A?
(a) Carries blood from an organ towards the heart
(b) Always carry oxygenated blood with single exception
(c) Carries blood from heart towards the organ
(d) All of these
(iv) Which of the following statements is incorrect?
(a) A has typically larger lumen than B.
(b) Walls of B are elastic enabling them to stretch and shrink during changes in blood pressure
(c) Flow of blood is slower in A than in B
(d) None of these
(v) Blood pressure in the pulmonary artery is

Our body needs to remove the wastes that build up from cell activities and from digestion. It these wastes are not removed, then our cells can stop working and we can get very sick. The organs of our excretory system help to release wastes from our body. The excretory system consists of a pair of kidney, a pair of ureters, a urinary bladder and a urethra. Each kidney is made up of nearly one million complex tubular structures called nephrons. The formation of urine involves various processes that takes place in the different parts of the nephron. Each nephron consists of a cup-shaped upper end called Bowman's capsule containing a bunch of capillaries called glomerulus. Bowman's capsule leads to tubular structure-proximal convoluted tubule, loop of Henle and distal convoluted tubule which ultimately joins the collecting tubule.
(i) The following substances are the excretory products in animals. Choose the least toxic form.

(ii) The outline of principal events of urination is given below in random manner.
(I) Stretch receptors on the wall of urinary bladder send signals to the CNS.
(II) The bladder fills with urine and becomes distended.
(III) Micturition
(IV) CNS passes on motor messages to initiate the contraction of smooth muscles of bladder and simultaneous relaxation of urethral sphincter.
The correct sequence of the events is

(iii) A person who is not taking food or beverages will have ___________ in urine.

(iv) Glomerular filtrate is first collected by

(v) The given figure represents a single nephron from a mammalian kidney. Identify the labelled parts, match them with the options (i-iv) and select the correct answer.

(I) The site of ultrafiltration
(II) Collect the urine and make it more concentrated
(III) The main site for the reabsorption of glucose and amino acids
(IV) Largely responsible for the maintenance of blood pH

All living cells need nutrients,O₂ and other essential substances. Also, the waste and harmful substances need to be removed continuously for healthy functioning of cells. So, a well developed transport system is mandatory for living organisms. Complex organisms have special fluids within their bodies to transport such materials. Blood is the most commonly used body fluid by most of the higher organisms. Lymph also helps in the transport of certain substances.
(i) Which of the following does not exhibit phagocytic activity?

(ii) Amount of blood corpusles in changed in dengue fever. One of the common symptoms observed in people infected with dengue fever is

(iii) Why are WBCs called soldiers of the body?
(a) They are capable of squeezing out of blood capillaries.
(b) They are manufactured in bone marrow.
(c) They fight against disease causing germs.
(d) They have granular cytoplasm with lobed nucleus.
(iv) Name the blood cells, whose reduction in number can cause clotting disorder, leading to excessive loss of blood from the body

(v) Which of the following is the correct feature oflymph?
(a) It is similar to the plasma of blood, but is colourless and contains less proteins.
(b) It is similar to the WBCs of blood, but is colourless and contain more proteins.
(c) It is similar to the RBCs of blood and red in colour.
(d) It contains more fats

After the discovery of large number of elements it became necessary to classify them and arrange them in a regular manner in order of their periodic properties. In 1817, Johann Wolfgang Dobereiner tried to arrange the elements with similar properties into groups. He identified some groups of three elements having similar physical and chemical properties, known as Dobereiners triads.
In 1865, John Newlands arranged all known elements in the order of increasing atomic masses and found that the properties of every eighth element are similar to the properties of the first element.
(i) If CI, Br, I is a Dobereiners triad and the atomic masses of CI and I are 35.5 and 127 respectively, then the atomic mass of Br is

(ii) Example of Dobereiner's triad is

(iii) A and B are two elements having similar properties which obey Newlands' law of octaves. How many elements are there in between A and B?

(iv) According to the Newlands' law of octaves, the properties of magnesium are similar to those of

(v) On what basis the elements are arranged in Dobereiner's triad?

Mendeleev arranged the 63 elements known at that time in order of their ascending atomic masses and prepared a periodic table. Mendeleev's periodic table contains vertical columns called 'groups' and horizontal rows called 'periods': Elements with similar properties were placed in same groups.
The basis of Mendeleev's classification is his periodic law which states that:
(I) Atomic mass is the fundamental property of elements.
(II) The physical and chemical properties of elements are periodic function of their atomic masses.
(i) Which of the following metals is not placed in eighth group of Mendeleev's periodic table?

(ii) In Mendeleevs periodic table, silver belongs to IB group. The group to which silver belongs in the modern periodic table is

(iii) In Mendeleev's periodic table, gaps were left for the elements to be discovered later. Which of the following elements found a place in the periodic table later?

(iv) The properties of eka-aluminium predicted by Mendeleev were the same as properties of which element that was discovered later?

(v) Which of the following statements is not correct about Mendeleev's periodic table?
(a) In the mendeleev's periodic table, some places were left vacant for new elements which were not discovered at that time.
(b) Group VIII like groups I-VII has been divided into two sub-groups A and B.
(c) The group of an element in the periodic table represents its valency.
(d) Li and C belong to same period in Mendeleevs periodic table.

In 1913, Henry Moseley showed that the atomic number of an element is the more fundamental property than its atomic mass. Accordingly, Mendeleev's periodic law was modified and atomic number was adopted as the basis of modern periodic table.
In this periodic table, the elements are arranged in increasing order of their atomic numbers.
There are 18 vertical columns in the periodic table which constitute 18 groups or families. The groups are numbered as 1, 2, 3, ... up to 18. All the members of a particular group have similar outer shell electronic configuration. There are seven horizontal rows of the periodic table which are known as periods.
(i) According to modern periodic law, the properties of elements are the periodic function of their

(ii) All the elements in a period in the periodic table have the same

(iii) Which of the following combinations of elements belong to the same group?

(iv) The atoms of elements belonging to the same group of periodic table have same number of

(v) In the periodic table, the element with atomic number 16 will be placed in the group

Maximum number of electrons that can be accommodated in a shell is given by the formula: 2n², where n is the number of the outermost from the nucleus.
For example,
K shell - 2 x (1)² => 2, hence, K-shell can accommodate maximum 2 electrons.
L shell - 2 x (2)² => 8, hence, L-shell can accommodate maximum 8 electrons.
In the modern periodic table, elements are placed according to their electronic configuration. The elements present in any group have the same number of valence electrons. The elements present in any period contain the same number of shells. The first period of the modern periodic table corresponds to the filling of electrons in the first energy shell, i.e., K-shell, first period has two elements. The second period of the periodic table corresponds to the filling of electrons in the second energy shell, i.e., L-shell, second period contains eight elements. The third, fourth, fifth, sixth and seventh periods have 8, 18, 18,32 and 32 elements respectively.
(i) Electronic configuration of an element 'X' is 2, 1. The number of elements present in the period to which 'X'belongs is

(ii) Among the given elements A, B, C, D and E with atomic numbers 2, 3, 7, 10 and 30 respectively, which of these belong to the same period?

(iii) The elements A, B, C and D have atomic numbers 4, 12, 17 and 19 respectively. Which pair of elements belong to the same period?

(iv) Which of the following have the same number of electrons in outermost shell?
(a) Elements with atomic numbers 3, 11, 19
(b) Elements with atomic numbers 14, 15, 16
(c) Elements with atomic numbers 12, 20, 28
(d) Elements with atomic numbers 10, 18, 26
(v) Which of the following elements has two shells and both are completely filled?

All the elements on the left side and in the middle of the periodic table (except hydrogen) are metallic elements or metals. Also, majority of elements in periodic table are metals. In the modern periodic table, the metals are separated from non-metals by a zig-zag line. Some non-metals are gases, some are liquids and rest are solids at room temperature. They generally differ from metals in appearance and in other physical properties. Some elements that lie along the zig-zag line that separates metals from non-metals, have properties that fall between those of metals and non-metals. These elements are regarded as semi-metals or metalloids.
(i) From the given set of metals and non-metals, identify the non-metals.
 \(\mathrm{S}, \mathrm{Mg}, \mathrm{Al}, \mathrm{P}, \mathrm{N}, \mathrm{Na}, \mathrm{K}\)

(ii) Which of the following groups contains metals, non-metals and metalloids?

(iii) Which of the following elements is a metalloid?

(iv) Silicon is a metalloid because
(a) its valency is 4
(b) it has three electron shells
(c) it shows properties of both metals and non-metals
(d) it is a liquid metal
(v) The lightest metal is

A series of organic compounds having same functional group, with similar or almost identical chemical characteristics in which all the members can be represented by the same general formula and the two consecutive members of the series differ by -CH₂ group or 14 mass unit in their molecular formulae is called a homologous series. For example, all the members of alcohol family can be represented by the general formula, C_nH_2n+1 OH where, n may have the values 1, 2, 3, ... etc. The various members of a particular homologous series are called homologues. The physical properties such as density, melting point, boiling point, solubility, etc. of the members of a homologous series show almost regular variation in ascending or descending the series.
(i) Which of the following is not a characteristic of members of a homologous series?

(ii) All the members of homologous series of alkynes have the general formula

(iii) Which of the following statements is not correct?

(iv) Identify the correct statements.
(I) As the molecular mass increases in any homologous series, a gradation in physical properties is seen.
(II) The melting and boiling points decrease with increasing molecular mass.
(III) Other physical properties such as solubility in a particular solvent decreases with increasing molecular mass.
(IV)The chemical properties, which are determined solely by the functional group, remain similar in a homologous series

(v) The table shows the formulae of three organic compounds that belong to the same homologous series.

What is the general formula of this series?

When an element exists in two or more different forms in the same physical state, these different forms are called allotropes and the phenomenon is known as allotropy. Allotropes have similar chemical properties but they differ in their physical properties. Carbon exists in crystalline and amorphous forms. In crystalline form, it occurs as diamond, graphite and fullerenes. Diamond is a colourless, transparent substance having extraordinary brilliance. It is the hardest natural substance known. It is used for cutting marble, granite and glass. Graphite is a greyish-black, opaque substance. It is lighter than diamond i.e., it has lower density. It has sheet like structure having hexagonal layers. One layer slides over the other layer which makes it soft to touch. It is the reason that graphite is used as a lubricant.
(i) Substance X is a moderate conductor of electricity. Substance X has the structure shown below:

Which statements about substance X are correct?
(I) It is a covalent compound.
(II) It has a giant molecular structure.
(III) It has the same structure as graphite
(IV) It has the same structure as diamond

(ii) Which of the following is correct about the structure of diamond?

(iii) Which three allotropes of carbon, do the given figure represents.

(iv) Identify the incorrect statement(s).
(I) Diamond is the hardest substance known while graphite is smooth and slippery.
(II) Diamond is made up of billions of carbon atoms. Each carbon atom is bonded to four other carbon atoms in a tetrahedral manner to form a giant lattice. All carbon atoms are bonded by strong covalent bonds.
(III) Graphite is a poor conductor of electricity unlike other non-metals.
(IV) Graphite has a giant covalent structure that is made up of layers of carbon atoms. In each layer, each carbon atom is bonded to three other carbon atoms to form hexagonal rings of carbon atoms.

(v) Structures Qf two different forms of carbon are given below:

Identify the two forms (I and II respectively) and how are they related to each other?

As neutral atom carbon has electronic configuration K L. To gain inert gas configuration carbon can either 2, 4 donate 4 valence electrons (helium gas configuration) or gain 4 electrons (neon gas configuration), but it cannot do so. To acquire inert gas configuration carbon can only share its 4 valence electrons with other atoms forming covalent bonds. A covalent bond can be defined as a chemical bond formed between two atoms by mutual sharing of valence electrons so that each atom acquires the stable electronic configuration of the nearest noble gas. The concept of covalent bonds was given by Langmuir and Lewis to explain bonding in non-ionic compounds. The covalent bonds are of three types. If each atom contributes one electron, the covalent bond formed is called a single covalent bond and is represented by a single line (-) and if each atom contributes two electrons, the covalent bond formed is called a double bond and is represented by a double line (=) and if each atom contributes three electrons, the covalent bond formed is called a triple bond and is represented by a triple line (=).
(i) Which of the following do not contain a double bond?
I. S02
II. NH3
III. HCl
IV. 02

(ii) Which of the following contains a triple bond?

(iii) The shared pair of electrons is said to constitute a _______________ bond between two hydrogen atoms.

(iv) Which of the following molecules has all its atoms joined together by double covalent bonds?

(v) Chlorine forms a diatomic molecule, Cl₂ . The electron dot structure for this molecule is

Two allotropic forms of carbon which are crystalline in nature, are diamond and graphite. They differ physically but chemically they are similar. Diamond is the hardest crystalline form of carbon. In diamond, each carbon atom is linked to four other carbon atoms by covalent bonds. In graphite, each carbon atom is linked to three other carbon atoms by covalent bond. Graphite is relatively soft and greasy. It is also a good conductor of electricity. The C-C bond length in graphite is 141.5 pm while in diamond it is 154 pm.
(i) Which of the following is a good conductor of heat and electricity?

(ii) Graphite is a good conductor of electricity because

(iii) Which of the following types of binding forces is present in the structure of diamond?

(iv) Diamond is not a good conductor of electricity because

(v) Which of the following is the structure of diamond?

The compounds which have the same molecular formula but differ from each other in physical or chemical properties are called isomers and the phenomenon is called isomerism. When the isomerism is due to difference in the arrangement of atoms within the molecule, without any reference to space, the phenomenon is called structural isomerism. In other words, structural isomers are compounds that have the same molecular formula but different structural formulas, i.e., they are different in the order in which different atoms are linked. In these compounds, carbon atoms can be linked together in the form of straight chains, branched chains or even rings.
(i) Which of the following sets of compounds have same molecular formula?

(ii) In order to form branching, an organic compound must have a minimum of

(iii) Which of the following is an isomeric pair?

(iv) Among the following the one having longest chain is

(v) The number of isomers of pentane is

The chemical reactivity of an element depends upon its electronic configuration. All elements having less than eight electrons in the outermost shell show chemical reactivity. During chemical reactions, atoms of all elements tend to achieve a completely filled valence shell. Metals are electropositive in nature. They have tendency to lose one or more electrons present in the valence shell of their atoms to form cations and achieve nearest noble gas configuration. The compounds formed by the transfer of electrons from one element to other are known as ionic or electrovalent compounds.
(i) The electronic configurations of three elements X, Y and Z are:
            X : 2                  Y: 2, 8, 7                     Z : 2, 8, 2
Which of the following is correct regarding these elements?

(ii) Element X reacts with element Y to form a compound Z. During the formation of compound Z, atoms of X lose one electron each whereas atoms of Y gain one electron each. Which of the following properties is not shown by compound Z?

(iii) Which of the following is correct representation of formation of magnesium chloride?

	(d) None of these

(iv) The electronic configuration of sodium ion is

(v)Which of the following represents an electropositive element?

The arrangement of metals in a vertical column in the decreasing order of their reactivities is called the reactivity series or activity series of metals. The most reactive metal is at the top position of the reactivity series. The least reactive metal is at the bottom of the reactivity series.
Hydrogen, though a non-metal, has been included in the activity series of metals only for comparison. Apart from it, the hydrogen atom also has tendency to lose its valence electron and form cation which behaves like metal.
 \(\mathrm{H} \rightarrow \mathrm{H}^{+}+e^{-}\)
(i) Which metal can be displaced by copper from its salt solution?

(ii) An element 'X after reacting with acids liberates hydrogen gas and can displace lead and mercury from their salt solutions. The metal 'X is

(iii) the most reactive metal is

(iv) The metal which does not liberate hydrogen gas after reacting with acid is

(v) Which of the following metals does not react with water at all?
(I) Sodium
(II) Copper
(III) Aluminium
(IV) Lead

Metals as we know, are very useful in all fields, industries in particular. Non-metals are no less in any way. Oxygen present in air is essential for breathing as well as for combustion. Non-metals form a large number of compounds which are extremely useful, e.g., ammonia, nitric acid, sulphuric acid, etc.
Non-metals are found to exist in three states of matter. Only solid non-metals are expected to be hard however, they have low density and are brittle. They usually have low melting and boiling points and are poor conductors of electricity.
(i)____________ is a non-metal but is lustrous

(ii) Which of the following is known as 'King of chemicals'?

(iii) Which of the following non-metals is a liquid?

(iv) Hydrogen is used

(v) Generally, non-metals are bad conductors of electricity but 'X' which is a form of carbon is a good conductor of electricity and is an exceptional non-metal. 'X'is 

Ionic compound is a chemical compound in which ions are held together by ionic bonds. An ionic bond is the type of chemical bond in which two oppositely charged ions are held through electrostatic forces. We know that, metal atoms have loosely bound valence electrons in their valence shell and non-metal atoms need electrons in their valence shell to attain noble gas configuration. The metal atom loses the valence electrons while non-metal atom accepts these electrons. By losing electrons, metal atoms change to cations and by accepting electrons, non-metals form anions. Ionic compounds are generally solid and exist in the form of crystal. They have high melting and boiling points.
(i) Which of the following can change to a cation?

(ii) Which of the following can change to an anion?

(iii) Ionic compounds are soluble in _____________.

(iv) Which of the following statements is correct about ionic compounds?
I. They conduct electricity in solid state.
II. They conduct electricity in solutions.
III. They conduct electricity in molten state.

(v) Select the incorrect statement.

An element is a pure substance made up of same kind of atoms. At present, nearly 118 elements are known but all of them do not occur free in nature, some of them have been synthesized by artificial methods. Based on their properties, they are mainly classified as metals and non-metals. Metals are those elements which lose electrons and form positive ions i.e., they are electropositive in nature. They are generally hard, good conductors of heat and electricity, malleable, ductile and have striking lustre. They have a significant role to play in our daily life.
(i) Metals which are of vital importance to the national defence, energy and industry sector are called strategic metals. Which of the following is a strategic metal?

(ii) Which metal is the best conductor of electricity?

(iii) Which of the following metals is not a coinage metal?

(iv) Which of the following are the most malleable metals?
(I) Sodium
(II) Gold
(III) Potassium
(IV) Silver

Identify the correct statement(s).
(I) The wires that carry current in our homes have a coating of PVC or a rubber like material.
(II) School bells are made of metals.
(III) Metals do not conduct electricity.
(IV) Metals which produce a sound on striking a hard surface are said to be non-sonorous.

The acidic behaviour of acids is due to the presence of hydrogenil(H⁺)ions in them. They produce hydrogen ions in the presence of water. Water is a polar solvent and this property of water helps in weakening the bond between the ions and makes them soluble. Hence, acids and bases produce ions in aqueous solutions.
It may be noted that a dry Hel gas or a solution of hydrogen chloride in organic, nonpolar solvents like toluene or benzene do not show acidic properties. This is because hydrogen chloride does not undergo ionization in toluene.
The reason why Hel splits into H⁺ and CI^- ions in presence of water lies in the fact that water molecules, being polar, pull the H⁺ and Cl ^- ions apart and thus, the bond in Hel is broken

(i) Identify the wrong statement.

(ii) If the pH of a solution is 8, then its [H⁺] ion is

(iii) In terms of acidic strength, which one of the following is in the correct increasing order?

(iv) Which of the following compounds does not give H⁺ ions in aqueous solution?

(v) Four solutions labelled as P, Q, Rand Shave pH values 1, 9, 3 and 13 respectively.
Which of the following statements about the given solutions is incorrect?

A compound, X of sodium forms a white powder. It is a constituent of baking powder and is used in some antacids. When heated it gives a compound, Y which is anhydrous and absorbs water to become a hydrated salt. When this salt is kept in open air, it loses water molecules in a process called efflorescence. When dissolved in water it forms a strong base and a weak acid, Z.
(i) What is the compound, X?

(ii) The compound, Y is

(iii) What is the nature of the solution formed by dissolving Y in water?

(iv) Identify the compound, Z.

(v) Sodium carbonate is a basic compound because it is a salt of a

Sodium chloride obtained from sea water or from lakes contains many impurities such as sulphates of sodium and magnesium along with chlorides of calcium and magnesium. The chlorides of calcium and magnesium are particularly undesirable on account of their deliquescent nature.
For its purification, common salt is dissolved in minimum quantity of water to get a saturated solution from which insoluble impurities are filtered off. Then hydrogen chloride gas is passed through the saturated solution and the crystals of pure NaCl separate out. The soluble impurities remain in the mother liquor. The crystals are filtered, washed and dried.
(i) Select the correct statement regarding salt NaCl.

(ii) Nature of aqueous solution of common salt is

(iii) In the given series of reactions, Y and Z respectively are
²

(iv) Which of the following compounds is alkaline in aqueous medium?

(v) Some statements regarding salt NaCI are given below
(I) It is prepared by chlor-alkali process
(II) It is a white crystalline substance
(III) It also exists in the form of rocks and is called rock salt
(IV) It is a neutral salt, pH value of NaCI is 7

Chemically, Plaster of Paris (POP) is calcium sulphate hemihydrate, i.e., containing half molecule of water of crystallisation. It is represented by the formula, CaSO_{4 ·}1/2H₂O. Half molecule of water of crystallisation means that one water molecule is shared by two formula units of CaSO_4. Hence, we also represent its formula as (CaSO₄)_2·H₂O. The name, plaster of Paris, was given to this compound because for the first time, it was made from gypsum which was mainly found in Paris.
(i) The difference of water molecules in gypsum and plaster of Paris is

(ii) Plaster of Paris hardens by

(iii) Which of the following statements is incorrect?

(iv) Select the incorrect statement with respect to gypsum

(v) Plaster of Paris is obtained by

pH is quite useful to us in a number of ways in daily life. Some of its applications are:
Control of pH of the soil: Plants need a specific pH range for proper growth. The soil may be acidic, basic or neutral depending upon the relative concentration of H⁺ and OH^-. The pH of any soil can be determined by using pH paper. If the soil is too acidic, it can be corrected by adding lime to it. If the soil is too basic, it can be corrected by adding organic manure which contains acidic materials
Regaining shine of a tarnished copper vessel by use of acids: A copper vessel gets tarnished due to formation of an oxide layer on its surface. On rubbing lemon on the vessel, the surface is cleaned and the vessel begins to shine again. This is due to the fact that copper oxide is basic in nature, which reacts with the acid (citric acid) present in lemon to form a salt (copper citrate) which is washed away with water. As a result, the layer of copper oxide is removed from the surface of the vessel and the shining surface is exposed
(i) When black copper oxide placed in a beaker is treated with dilute HCl, its colour changes to

(ii) P is an aqueous solution of acid and Q is an aqueous solution of base. When these two are diluted separately, then

(iii) Which of the following acids is present in bee sting?

(iv) Sting of ant can be cured by rubbing the affected area with soap because

(v) The pH of soil X is 7.5 while that of soil Y is 4.5. Which of the two soils, should be treated with powdered chalk to adjust its pH?

Chemical equation is a method of representing a chemical reaction with the help of symbols and formulae of the substances involved in it. In a chemical equation, the substances which combine or react are called reactants and new substances produced are called products. A chemical equation is a short hand method of representing a chemical reaction. A balanced chemical equation has equal number of atoms of different elements in the reactants and products side. An unbalanced chemical equation has unequal number of atoms of one or more elements in reactants and products. Formulae of elements and compounds are not changed to balance an equation.
(i) Consider the following reaction:
pMg₃N₂ + qH₂O ⇾ rMg(OH)₂ + sNH₃
When the equation is balanced, the coefficients p, q, r, s respectively are

(ii) Which of the following information is not conveyed by a balanced chemical equation?

(iii) The balancing of chemical equations is in accordance with

(iv) Which of the following chemical equations is an unbalanced one?

(v) Which of the following statements is/are correct?

In decomposition reactions, a single reactant breaks down to form two or more products. A decomposition reaction is opposite to combination reaction. Thermal decomposition reactions use the energy in form of heat for the decomposition of reactants. Electrolytic decomposition reactions involve the use of electrical energy for the decomposition of reactant molecules. Photolysis or photochemical decomposition involves the use of light energy for the purpose of decomposition.
(i) Which of the following reactions is a decomposition reaction?

\({ (ii) \ } 2 \mathrm{~Pb}\left(\mathrm{NO}_{3}\right)_{2} \longrightarrow 2 \mathrm{PbO}+n A+\mathrm{O}_{2}\)
What is nA in the given reaction?

(iii) Amino acid is formed by the decomposition of which component of our diet?

(iv) Silver chloride on exposure to sunlight for a long duration turns grey due to
(I) the formation of silver by decomposition of silver chloride
(II) sublimation of silver chloride
(III) decomposition of chlorine gas from silver chloride
(IV) oxidation of silver chloride
The correct statement(s) is/are

(v) What type of chemical reaction takes place when electricity is passed through water?

Redox reactions are those reactions in which oxidation and reduction occur Simultaneously. A redox reaction is made up of two half reactions. In the first half reaction, oxidation takes place and in second half reaction, reduction occurs. Oxidation is a process in which a substance loses electrons and in reduction, a substance gains electrons. The substance which gains electrons is reduced and acts as an oxidising agent. On the other hand, a substance which loses electrons is oxidised and acts as a reducing agent.
(i) Which of the following is a redox reaction?

(ii) Identify the reaction in which H2 02 is acting as a reducing agent.

(iii) For the following reactions, identify the one in which H₂S acts as a reducing agent.

(iv) For the following reaction, identify the correct statement.
\(\mathrm{ZnO}+\mathrm{CO} \longrightarrow \mathrm{Zn}+\mathrm{CO}_{2}\)

(v) In the following reaction, which substance is reduced?
\(\mathrm{PbS}+4 \mathrm{H}_{2} \mathrm{O}_{2} \longrightarrow \mathrm{PbSO}_{4}+4 \mathrm{H}_{2} \mathrm{O}\)

In a balanced chemical reaction, equal number of atoms are present on both sides of reaction. A balanced chemical reaction is based on law of conservation of mass which means that total mass of reactants and products participating in a reaction must be equal. For example, a balanced chemical equation of burning of magnesium in oxygen to form magnesium oxide is written as :
\(2 \mathrm{Mg}+\mathrm{O}_{2} \longrightarrow 2 \mathrm{MgO}\)
The mass of reactants (2 x 24 + 32 = 80) is equal to the mass of products [2 x (24 + 16) = 80]
(i) In a reaction, 35 g of reactant, PQ breaks down into 20 g of product, P and an unknown amount of product, Q. Using the law of conservation of mass, weight of products, Q will be

(ii) When solid mercury (II) oxide is heated, liquid mercury and oxygen gas are produced. Which of the following statements is true regarding the balanced chemical equation for this process?
(a) 1 mole of mercury (II) oxide produces two moles of mercury and one mole of oxygen gas
(b) 2 moles of mercury (II) oxide produce one mole of mercury and one mole of oxygen gas
(c) 1 mole of mercury (II) oxide produces half mole of mercury and half mole of oxygen gas
(d) 2 moles of mercury (II) oxide produce 2 moles of mercury and one mole of oxygen gas
(iii) Which of the following laws is satisfied by a balanced chemical equation?

(iv) In the given chemical reaction
\(\mathrm{C}_{6} \mathrm{H}_{6(l)}+15 \mathrm{O}_{2(g)} \longrightarrow m \mathrm{CO}_{2(g)}+n \mathrm{H}_{2} \mathrm{O}_{(l)}\)
The values of m and n are respectively

(v) Sulphur dioxide reacts with oxygen to form sulphur trioxide. What would be the molar ratio of sulphur dioxide to sulphur trioxide?

In a chemical reaction, reactants are converted into products. The conversion of reactants into products in a chemical reaction is often accompanied by some features which can be observed easily. These easily observed features which take place as a result of chemical reaction are known as characteristics of chemicals reactions. Some important characteristics of chemical reactions are: 
(I) Evolution of heat 
(II) Formation of precipitate
(III) Change in colour
(IV) Change in temperature
(V) Change in state
Anyone of these general characteristics can tell us whether a chemical reaction has taken place or not.
(i) Reaction of magnesium with air is a/an

(ii) In the following reaction
\(\mathrm{Ca}_{(a q)}^{2+}+2 \mathrm{OH}_{(a q)}^{-} \longrightarrow \mathrm{Ca}(\mathrm{OH})_{2(s)}\)
precipitate of calcium hydroxide will be of

(iii) In the given reaction,
\(\mathrm{S}_{(s)}+\mathrm{O}_{2(g)} \longrightarrow \mathrm{SO}_{2}\)
the physical state of SO₂ is

(iv) Which one of the following processes involve chemical reactions?

(v) In which of the following reactions, high amount of heat energy will be evolved?

In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved temperature?

The pH of the gastric juices released during digestion is

Which of the following metals are obtained by electrolysis of their chlorides in molten state?
(i) Na   (ii) Ca   (iii) Fe   (iv) Cu

Carbohydrate in humans is stored in the form of

Select the mis-matched pair.

Three beakers labelled as A, B and C each containing 25 mL of water was taken. A small amount of NaOH, anhydrous CuSO₄ and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is (are) correct?
(i) In beakers A and B, exothermic process has occurred.
(ii) In beakers A and B, endothermic process has occurred.
(iii) In beaker C exothermic process has occurred.
(iv) In beaker C endothermic process has occured.

Sodium hydrogen carbonate when added to acetic acid evolves a gas.  Which of the following statements are true about the gas evolved?
(i) It turns lime water milky
(ii) It extinguishes a burning splinter
(iii) It dissolves in a solution of sodium hydroxide
(iv) It has a pungent odour

Which of the following non-metals is a liquid?

Which part of alimentary canal receives bile from the liver?

Which of the following is not associated with growth of plant?

The preparation of water from hydrogen and oxygen gas is accompanied by:

Identify the correct representation of reaction occurring during chlor-alkali process

Which of the following properly is generally not shown by metals?

Which one of the following will decide whether something is alive:

Junction between two neurons is called

Which of the following are exothermic processes?
(i) Reaction of water with quicklime
(ii) Dilution of an acid
(iii) Evaporation of water
(iv) Sublimation of camphor(crystals)

Calcium phosphate is present in tooth enamel.  Its nature is

Generally, non-metals are not lustrous. Which of the following nonmetal is lustrous?

Which of the first enzyme to mix with food in the digestive tract?

The substance that triggers the fall of mature leaves and fruits from plants is due to

Which among the following is /are double displacement reaction(s) ?
(i) Pb + CuCl₂ \(\rightarrow\) PbCl₂ + Cu
(ii) Na₂SO₄ + BaCl₂ \(\rightarrow\) BaSO₄ + 2NaCl
(iii) C + O₂ \(\rightarrow\) CO₂
(iv) CH₄ + 2O₂ \(\rightarrow\) CO₂ + 2H₂O

During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to

Generally, non-metals are not lustrous. Which of the following nonmetal is lustrous?

The kidneys in human beings are a part of the system for

Which of the following statement is correct about receptors?

During an exothermic reaction

Which of the following salts has no water of crystallization?

If copper is kept open in air, it slowly loses its shining brown surface and gains a green coating. It is due to the formation of

The kidneys in human beings are a part of the system for

Which statement is not true about thyroxin?

Three beakers labelled as A, B and C each containing 25 mL of water was taken. A small amount of NaOH, anhydrous CuSO₄ and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is (are) correct?
(i) In beakers A and B, exothermic process has occurred.
(ii) In beakers A and B, endothermic process has occurred.
(iii) In beaker C exothermic process has occurred.
(iv) In beaker C endothermic process has occured.

In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus shown below was set up.

which among the following statement(s) is (are) correct?
(i) Bulb will not glow because electrolyte is not acidic
(ii) Bulb will glow because NaOH is a strong base and furnishes ions for conduction.
(iii) Bulb will not glow because circuit is incomplete.
(iv) Bulb will not glow because it depends upon the type of electrolytic solution.

2 ml each of concentrated HCl, HNO₃ and a mixture of concentrated HCl and concentrated HNO₃ in the ratio of 3 : 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occured in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be

A few drops of iodine solution were added to rice water. The solution turned blue-black in colour. This indicates that rice water contains

Which of the following statements about transmission of nerve impulse is incorrect?

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?
(i) It is an endothermic reaction
(ii) It is an exothermic reaction
(iii) The pH of the resulting solution will be more than seven
((iv) The pH of the resulting solution will be less than seven

Which of the following is not a mineral acid?

Which one of the following properties is not generally exhibited by ionic compounds?

The correct sequence of anaerobic reactions in yeast is

Involuntary actions in the body are controlled by

Which information is not conveyed by a balanced chemical equation?

The nature of calcium phosphate is present in tooth enamel is

An alloy is

The correct sequence of anaerobic reactions in yeast is

Which of the following statements are true?
(i) Sudden action in response to something in the environment is called reflex action
(ii) Sensory neurons carry signals from spinal cord to muscles
(iii) Motor neurons carry signals from receptors to spinal cord
(iv) Impulse from a receptor to a muscle or a gland is called reflex arc

What is the role of a catalyst in a chemical 

Dry ammonia gas has no action on litmus paper, but a solution of a ammonia in water turns red litmus paper blue, why is it so?

What is synapse?

What are fossil fuels?

Chlorine, bromine and iodine form a Dobereiner's triad. The atomic masses of chlorine and iodine are 35.5 and 126.9 respectively. Predict the atomic mass of bromine.

The decomposition of vegetable matter in to compost is an example of what type of reaction?

What are gustatory receptors?

A normal pea plant bearing coloured flowers suddenly start producing white flowers. What could be the possible cause?

Name the type of particles which act as prism in the formation of rainbow in the sky

Name the gas which burns with pop sound.

(a) Give Arrhenius definition of an acid and a base.
(b) Choose strong acid and strong base from the following:
 \(CH_3COOH,\ NH_4OH,\ KOH,\ HCl\)

Name the hormone secreted by thyroid gland.

What is renewable source of energy?

Why was the system of classification of elements into triads not found suitable? 

Give an example of photochemical reactions.

What is reflex action?

What is meant by the 'calorific value' of a fuel? How is it determined? Arrange the following fuels in a decreasing order of their calorific values: Kerosene, Coal, LPG.

Lithium, sodium and potassium form a Dobereiner's triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.

Give the formula for quicklime.

What is synapse?

What is meant by the 'calorific value' of a fuel? How is it determined? Arrange the following fuels in a decreasing order of their calorific values: Kerosene, Coal, LPG.

Lithium, sodium and potassium form a Dobereiner's triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.

Name the different forms of energy required for breaking down the reactants in decomposition reaction.

(a) Give Arrhenius definition of an acid and a base.
(b) Choose strong acid and strong base from the following:
 \(CH_3COOH,\ NH_4OH,\ KOH,\ HCl\)

Name the hormone secreted by thyroid gland.

What is meant by the 'calorific value' of a fuel? How is it determined? Arrange the following fuels in a decreasing order of their calorific values: Kerosene, Coal, LPG.

Chlorine, bromine and iodine form a Dobereiner's triad. The atomic masses of chlorine and iodine are 35.5 and 126.9 respectively. Predict the atomic mass of bromine.

Name the different forms of energy required for breaking down the reactants in decomposition reaction.

(a) Give Arrhenius definition of an acid and a base.
(b) Choose strong acid and strong base from the following:
 \(CH_3COOH,\ NH_4OH,\ KOH,\ HCl\)

Name the hormone secreted by thyroid gland.

What is meant by the 'calorific value' of a fuel? How is it determined? Arrange the following fuels in a decreasing order of their calorific values: Kerosene, Coal, LPG.

Chlorine, bromine and iodine form a Dobereiner's triad. The atomic masses of chlorine and iodine are 35.5 and 126.9 respectively. Predict the atomic mass of bromine.

Which term is used to indicate the development of unpleasant smell and taste in butter and oil containing food?

Name the part of hind brain which takes part in regulation of respiration.

What is geothermal energy?

Lithium, sodium and potassium form a Dobereiner's triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.

Arun took a pale green substance X in a test tube, and heated it over a flame. He observed a color change along with evolution of two gases with the smell of burning sulphur
(a) Identify X.
(b) Identify the product formed.
(c) Write the equation.
(d) Identify the type of chemical reaction.

Name one endocrine gland which performs dual function.

Which one of the following is a renewable resource?
Natural gas, Petrroleum, Ground water, Coal

State modern periodic law of classification of elements.

A solution reacts with crushed egg-shells to give a gas that turns lime-water milky.  The solution contains.

During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to

Sodium carbonate is a basic salt because it is a salt of

If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done?

Lime water is

Which of the statements about the reaction below are incorrect?
2PbO(s) + C(s) \(\rightarrow\) 2Pb(s) + CO₂(g)
(a) Lead is getting reduced      
(b) Carbon dioxide is getting oxidized
(c) Carbon is getting oxidized    
(d) Lead oxide is getting reduced.

Which of the following statements about the given reaction are correct?
3Fe(s) + 4H₂O(g) \(\rightarrow\) Fe₃O₄(s) + 4H₂(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent

Three beakers labelled as A, B and C each containing 25 mL of water was taken. A small amount of NaOH, anhydrous CuSO₄ and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solutions contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is (are) correct?
(i) In beakers A and B, exothermic process has occurred.
(ii) In beakers A and B, endothermic process has occurred.
(iii) In beaker C exothermic process has occurred.
(iv) In beaker C endothermic process has occured.

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?
(i) It is an endothermic reaction
(ii) It is an exothermic reaction
(iii) The pH of the resulting solution will be more than seven
((iv) The pH of the resulting solution will be less than seven

Chemically rust is

Which of the following statements about the given reaction are correct?
3Fe(s) + 4H₂O(g) \(\rightarrow\) Fe₃O₄(s) + 4H₂(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent

A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?

In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?

If reaction between nitrogen and hydrogen to form ammonia is exothermic, then it will be accompanied by

Which of the following feature is common to both physical and chemical change?

On heating blue coloured powder of copper (II) nitrate in a boiling tube, copper oxide (black), oxygen gas and a brown gas X is formed.
(a) Write a balanced chemical equation of the reaction.
(b) Identify the brown gas X evolved.
(c) Identify the type of reaction.
(d) What could be the pH range of aqueous solution of the gas X?

For making cake, baking powder is taken.  If at home your mother uses baking soda instead of baking powder in cake,

(a) How will it affect the taste of the cake and why?

(b) How can baking soda be converted into baking powder?

(c) What is the role of tartaric acid added to baking soda?

Explain the following
(a) Reactivity of Al decreases if it is dipped in HNO₃.
(b) Carbon cannot reduce the oxides of Na or Mg
(c) NaCl is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state.
(d) Iron articles are galvanised 
(e) Metals like Na, K, Ca and Mg are never found in their free state in nature.

Explain the mechanism of photosymthesis.

How does chemical coordination take place in animals?

Define the term decomposition reaction. Give one example each of thermal decomposition and electrolytic decomposition.

Write the chemical equation of the reaction with an example each in which the following change has taken place:
(i) Change in colour
(ii)Change in temperature
(iii) Formation of precipitate.

A sanitary worker uses a white chemical having strong smell of chlorine gas to disinfect the water tank.
(i) Identify the chemical compound, write its chemical formula.
(ii) Give chemical equation for its preparation.
(iii) Write its two uses other than disinfection.

Explain the action of dilute hydrochloric acid on the following with chemical equation:
(i) magnesium ribbon
(ii) sodium hydroxide
(iii) crushed egg shells

Why should a magnesium ribbon be cleaned before burning in air?

Balance the following chemical equations.
(a) HNO₃ + Ca(OH)₂ \(\rightarrow\) Ca(NO₃)₂ + H₂O
(b) NaOH + H₂SO₄ \(\rightarrow\) Na₂SO₄ + H₂O
(c) NaCl + AgNO₃ \(\rightarrow\) AgCl + NaNO₃
(d) BaCl₂ + H₂SO₄ \(\rightarrow\) BaSO₄ + HCl

A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed. Write the chemical reaction involved and also mention the type of the chemical reaction.

Explain and name the type of reaction seen when iron reacts with hydrochloric acid.

When Hydrogen gas is passed over heated copper (II) oxide, copper and steam are formed. Write the balanced chemical equation with physical states for this reaction. State what kind of chemical reaction is this?

Deoxygenated blood enters the heart through

Complete digestion of carbohydrates, proteins and fats takes place in

Tiny pores present on the surface of the leaf are called

From the list given below pick the item that is not a natural resource

Given below are a few statements related to biodiversity. Pick those that correctly describe the concept of biodiversity
(i) Biodiversity refers to the different species of flora and fauna present in an area
(ii) Biodiversity refers to only the flora of a given area
(iii) Biodiversity is greater in a forest
(iv) Biodiversity refers to the total number of individuals of a particular species living in an area 

Indicate the flow of energy in an ecosystem. Why is it unidirectional? Justify.

What are decomposers? List two consequences of their absence in an ecosystem?

Suggest any four activities in daily life which are eco-friendly.

Give two differences between food chain and food web.

Name the wastes which are generated in your house daily. What measures would you take for their disposal?

In the context of conservation of natural resources, explain the terms reduce, recycle and reuse. From among the materials that we use in daily life, identify two materials for each category.

Prepare a list of five activities that you perform daily in which natural resources can be conserved or energy utilisation can be minimised.

Is water conservation necessary? Give reasons.

Suggest a few useful ways of utilising waste water.

What is the importance of forest as a resource?

Write laws of refraction. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab.

Define power of a lens. What is its unit? One student uses a lens of focal length 50 cm and another of - 50 cm. What is the nature of the lens and its power used by each of them?

(i) One half of a convex lens of focal length 10 cm is converted with a black paper. Can such a lens produce an image of a complete object placed at a distance of 30 cm from the lens? Draw ray diagram to justify your answer.
(ii) A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 15 cm. Find nature, position and size of the image.

(a) Define focal length of a spherical lens.
(b) A divergent lens has a focal length of 30 cm. At what distance should an object of height 5 cm from the optical centre of the lens be placed so that its image is formed 15 cm away from the lens? Find the size of the image also.
(c) Draw a ray diagram to show the formation of image in the above situation.

(a) Define optical centre of a spherical lens.
(b) A divergent lens has a focal length of 20 cm At what distance should an object of height 4 cm from the optical centre of the lens be placed so that its image is formed 10 cm away from the lens. Find the size of the image also.
(c) Draw a ray diagram to show the formation of image in above situation.

Does geographical isolation of individuals of a species lead to formation of a new species? Provide a suitable explanation.

Differentiate between inherited and acquired characters. Give one example for each type.

Give reasons why acquired characters are not inherited.

In the following crosses write the characteristics of the progeny

Study the following cross and showing self-pollination in F1, fill in the blank answer the question that follows
\(\underset { Round,yellow }{ RRYY } \times \underset { Wrinkled,green }{ rryy } F1-\underset { Round,yellow }{ Rr\quad Yy\times } \)

Write two points of difference between asexual and sexual types of reproduction. Describe why variations are observed in the offspring formed by sexual reproduction.

Distinguish between a gamete and zygote. Explain their roles in sexual reproduction.

How does fertilisation take place? Fertilisation occurs once in a month. Comment.

What is the placenta? Mention its role during pregnancy?

Reproduction is essentially a phenomenon that is not survival of an individual but for the stability of a species. Justify.

An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.
(a) Identify the element.
(b) Write the electronic configuration.
(c) Write the balanced equation when it burns in the presence of air.
(d) Write a balanced equation when this oxide is dissolved in water.
(e) Draw the electron dot structure for the formation of this oxide.

Atomic number of a few elements are given below 10, 20, 7, 14
(a) Identify the elements.
(b) Identify the Group number of these elements in the Periodic Table.
(c) Identify the Periods of these elements in the Periodic Table.
(d) What would be the electronic configuration for each of these elements?
(e) Determine the valency of these elements.

(a) Electropositive nature of the element(s) increases down the group and decreases across the period
(b) Electronegativity of the element decreases down the group and increases across the period
(c) Atomic size increases down the group and decreases across a period (left to right)
(d) Metallic character increases down the group and decreases across a period.
On the basis of the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9.
(a) Name the most electropositive element among them.
(b) name the most electronegative element.
(c) Name the element with smallest atomic size.
(d) Name the element which shows maximum valency.

An element A which is a yellow solid at room temperature shows catenation and allotropy. A forms two oxides which are also formed during the thermal decomposition of ferrous sulphate crystals and are the major air pollutants.
(a) Identify the element A
(b) Write the electronic configuration of A
(c) Write the balanced chemical equation for the thermal decomposition of ferrous sulphate crystals?
(d) What would be the nature (acidic/ basic ) of oxides formed?
(e) Locate the Position of the element in the Modern Periodic Table.

An element X of group 15 exists as diatomic molecule and combines with hydrogen at 773 K in presence of the catalyst to form a compound, ammonia which has a characteristic pungent smell. 
(a) Identify the element X. How many valence electrons does it have?
(b) Draw the electron dot structure of the diatomic molecule of X. What type of bond is formed in it?
(c) Draw the electron dot structure for ammonia and what type of bond is formed in it?

A salt X is formed and a gas is evolved when ethanoic acid reacts with sodium hydrogen carbonate. Name the salt X and the gas evolved. Describe an activity and draw the diagram of the apparatus to prove that the evolved gas is the one which you have named. Also, write chemical equation of the reaction involved.

a) What are hydrocarbons? Give examples
b) Give the structural differences between saturated and unsaturated hydrocarbons with two example each.
c) What is a functional group? Give example of four different functional groups.

Name the reaction which is commonly used in the conversion of vegetable oils to fats. Explain the reaction involved in detail.

Esters are sweet-smelling substances and are used in making perfumes. Suggest some activity and the reaction involved for the preparation of an ester with well labeled diagram.

How would you bring about the following conversions? Name the process and write the reaction involved.
a) Ethanol to ethene.
b) Propanol to propanoic acid

Describe the alimentary canal of man.

Explain the process of breathing in man.

Explain the important of soil for plant growth.

How do carbohydrates, proteins and fats get digested in human beings?

Explain the mechanism of photosymthesis.

A salt X is formed and a gas is evolved when ethanoic acid reacts with sodium hydrogen carbonate. Name the salt X and the gas evolved. Describe an activity and draw the diagram of the apparatus to prove that the evolved gas is the one which you have named. Also, write chemical equation of the reaction involved.

a) What are hydrocarbons? Give examples
b) Give the structural differences between saturated and unsaturated hydrocarbons with two example each.
c) What is a functional group? Give example of four different functional groups.

Name the reaction which is commonly used in the conversion of vegetable oils to fats. Explain the reaction involved in detail.

a) Write the formula and draw electron dot structure of carbon tetrachloride?
b) What is saponification? Write the reaction involved in this process.

Esters are sweet-smelling substances and are used in making perfumes. Suggest some activity and the reaction involved for the preparation of an ester with well labeled diagram.

An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.
(a) Identify the element.
(b) Write the electronic configuration.
(c) Write the balanced equation when it burns in the presence of air.
(d) Write a balanced equation when this oxide is dissolved in water.
(e) Draw the electron dot structure for the formation of this oxide.

Atomic number of a few elements are given below 10, 20, 7, 14
(a) Identify the elements.
(b) Identify the Group number of these elements in the Periodic Table.
(c) Identify the Periods of these elements in the Periodic Table.
(d) What would be the electronic configuration for each of these elements?
(e) Determine the valency of these elements.

Mendeleev' predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium.
(a) Name the elements which have taken the place of these elements.
(b) Mention the group and the period of these elements in the Modern Periodic Table.
(c) Classify these elements as metals, non-metals or metalloid.
(d) How many valence electrons are present in each one of them?

(a) Electropositive nature of the element(s) increases down the group and decreases across the period
(b) Electronegativity of the element decreases down the group and increases across the period
(c) Atomic size increases down the group and decreases across a period (left to right)
(d) Metallic character increases down the group and decreases across a period.
On the basis of the above trends of the Periodic Table, answer the following about the elements with atomic numbers 3 to 9.
(a) Name the most electropositive element among them.
(b) name the most electronegative element.
(c) Name the element with smallest atomic size.
(d) Name the element which shows maximum valency.

An element A which is a yellow solid at room temperature shows catenation and allotropy. A forms two oxides which are also formed during the thermal decomposition of ferrous sulphate crystals and are the major air pollutants.
(a) Identify the element A
(b) Write the electronic configuration of A
(c) Write the balanced chemical equation for the thermal decomposition of ferrous sulphate crystals?
(d) What would be the nature (acidic/ basic ) of oxides formed?
(e) Locate the Position of the element in the Modern Periodic Table.

Does geographical isolation of individuals of a species lead to formation of a new species? Provide a suitable explanation.

Bacteria have a simpler body plan when compared with human beings. Does it mean that human beings are more evolved than bacteria? Provide a suitable explanation.

All the human races like Africans, Asians, Europeans, Americans and others might have evolved from a common ancestor. Provide a few evidences in support of this view.

Differentiate between inherited and acquired characters. Give one example for each type.

Give reasons why acquired characters are not inherited.

Indicate the flow of energy in an ecosystem. Why is it unidirectional? Justify.

What are decomposers? List two consequences of their absence in an ecosystem?

Suggest any four activities in daily life which are eco-friendly.

Give two differences between food chain and food web.

Name the wastes which are generated in your house daily. What measures would you take for their disposal?

Size of image of an object by a mirror having a focal length of 20 cm is observed to be reduced to 1/3 rd of its size. At what distance the object has been placed from the mirror? What is the nature of the image and the mirror?

The image of a candle flame formed by a lens is obtained on a screen placed on the other side of the lens. If the image is three times the size of the flame and the distance between lens and image is 80 cm, at what distance should the candle be placed from the lens? What is the nature of the image at a distance of 80 cm and the lens?

(i) One half of a convex lens of focal length 10 cm is converted with a black paper. Can such a lens produce an image of a complete object placed at a distance of 30 cm from the lens? Draw ray diagram to justify your answer.
(ii) A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 15 cm. Find nature, position and size of the image.

(a) Define focal length of a spherical lens.
(b) A divergent lens has a focal length of 30 cm. At what distance should an object of height 5 cm from the optical centre of the lens be placed so that its image is formed 15 cm away from the lens? Find the size of the image also.
(c) Draw a ray diagram to show the formation of image in the above situation.

(a) Define optical centre of a spherical lens.
(b) A divergent lens has a focal length of 20 cm At what distance should an object of height 4 cm from the optical centre of the lens be placed so that its image is formed 10 cm away from the lens. Find the size of the image also.
(c) Draw a ray diagram to show the formation of image in above situation.

Write two points of difference between asexual and sexual types of reproduction. Describe why variations are observed in the offspring formed by sexual reproduction.

Distinguish between a gamete and zygote. Explain their roles in sexual reproduction.

What are various ways to avoid pregnancy? Elaborate any one method.

How does fertilisation take place? Fertilisation occurs once in a month. Comment.

What is the placenta? Mention its role during pregnancy?

Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.

Two ores A and B were taken. On heating ore A gives CO₂ whereas, ore B gives SO₂ .What steps will you take to convert them into metals?

What is an alloy? How is an alloy made? List two purpose of making alloys. Mention the constituents and two properties of each of the following alloys.
(i) Stainless steel
(ii) Brass

(i) Why Sulphuric acid is called the 'king of chemicals'?
(ii) Name the gas evolved when :
      (a) Concentrated Sulphuric acid acts on Sulphur.
      (b) Dilute Sulphuric acid acts on Sodium carbonate.
(iii) State the colour change you would observe on adding concentrated sulphuric acid to :
      (a) Blue Copper sulphate crystals.
      (b) Colourless cane-sugar crystals.

(a) Write chemical equations for the reactions involved in obtaining pure alumina from the mineral bauxite which has impurities of iron oxide and silica.
(b) Draw a labelled diagram of the electrolytic tank cell used for the extraction of aluminium from alumina.

(a) What is a 'solar cell'?
(b) Why is biogas considered an ideal fuel for domestic use?
(c) Name a device in which controlled chain reaction is used.

(a) Why is the Solar Cooker box covered with a plane glass plate?
(b) Why is energy of water flowering in a river considered to be an indirect form of solar energy?
(c) How is the fission of nucleus brought about?

(a) State one limitation of solar energy available from solar cells.
(b) What is the minimum wind velocity required to obtain useful energy with a windmill?
(c) Define the term 'nuclear fission'.

Which is the process used to harness nuclear energy these days? Explain it briefly.

a) How can solar energy be harnessed?
b) Mention any two limitations in using solar energy.
c) How are these limitations overcome?

(a) Give two uses of electromagnets.
(b) Name any two devices which use permanent magnets.

Distinguish between an electric motor and generator?

(a) Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet get deflected when a bar magnet or a current carrying loop is brought near it.
(b) Describe some salient features of magnetic lines of field. 

With the help of a labelled circuit diagram illustrate the pattern of field lines of the magnetic field around a current carrying straight long conducting wire. How is the right hand thumb rule useful to find direction of magnetic field associated with a current carrying conductor?

Explain with the help of a labelled diagram the distribution of magnetic field due to a current through a circular loop. Why is it that if a current carrying coil has 'n' turns the field produced at any point is n times as large as that produced by a single turn?

Draw a diagram showing endocrine glands in a male body. Label the following glands on it:
(i) Pituitary
(ii) Thyroid
(iii) Adrenal
(iv) Testes

What are hormones? State one function of each of the following hormone
(i) Thyroxin
(ii) Insulin.

Distinguish between voluntary and involuntary actions of our body.

What constitutes the central and peripheral nervous systems? How are the components of central nervous system protected?

Name various plant hormones. Also give their physiological effects on plant growth and development.

(a) State Ohm's Law.
(b) Draw a schematic diagram of the circuit for studying Ohm's Law.

If a 12 V battery is connected to the arrangement of resistances given below, calculate
(i) the total effective resistance of the arrangement and
(ii) the total current flowing in the circuit

Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit, another set of three bulbs of the same voltage are connected in parallel to the same source.
(a) Will the bulb in the two circuits glow with the same brightness? Justify your answer.
(b) Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason

State Ohm's law? How can it be verified experimentally? Does it hold good under all conditions? Comment

How will you infer with the help of an experiment that the same current flows through every part of the circuit containing three resistances in series connected to a battery?

Describe the alimentary canal of man.

Explain the important of soil for plant growth.

Explain the mechanism of photosymthesis.

Describe the process of urine formation in kidneys.

Explain the process of 'photosynthesis' in plants.List four factors which influence this process and describe how each of them affects the rate of the photosynthesis process.

A non-metal A which is the largest costituent of air, when heated with H₂ in 1 : 3 ratio in the presence of catalyst (Fe) gives a gas B. On heating with O₂ it gives an oxide C. If this oxide is passed into water in the presence of air it gives an acid D which acts as a strong oxidising agent.
(a) Identify A, B, C and D
(b) To which group of periodic table does this non - metal belong?

Of the three metals X, Y and Z, X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.

An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.

Two ores A and B were taken. On heating ore A gives CO₂ whereas, ore B gives SO₂ .What steps will you take to convert them into metals?

(a) Write chemical equations for the reactions involved in obtaining pure alumina from the mineral bauxite which has impurities of iron oxide and silica.
(b) Draw a labelled diagram of the electrolytic tank cell used for the extraction of aluminium from alumina.

(i) Name the raw materials used in the manufacture of sodium carbonate by Solvay process.

(ii) How is the sodium hydrogen carbonate formed during Solvay process separated from a mixture of \(NH_4Cl\) and \(NaHCO_3\)?

(iii) How is sodium carbonate obtained from sodium hydrogen carbonate?

(i) An aqueous solution has a pH value of 7.0.  Is this solution acidic, basic or neutral?

(ii) If H+ concentration of a solution is \(1\times 10^{-2}\ mol\ L^{-1},\) what is the pH value for it?

(iii) Which has a higher pH value, 1 M HCl or 1 M NaOH solution?

In the following schematic diagram for the preparation of hydrogen gas as shown in Figure, what would happen if following changes are made?

(a) In place of zinc granules, same amount of zinc dust is taken in the test tube.
(b) Instead of dilute sulphuric acid, dilute hydrochloric acid is taken.
(c) In place of zinc, copper turnings are taken.
(d) Sodium hydroxide is taken in place of dilute sulphuric acid and the tube is heated.

A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back.  On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y; it gives a compound Z, used for disinfecting drinking water.  Identity X, Y, G and Z.

A sulphate salt of Group 2 element of the Periodic Table is a white, soft substance.  Which can be moulded into different shapes by making its dough.  When this compound is left in open for sometime, it becomes a solid mass and cannot be used for moulding purposes.  Identify the sulphate salt and why does it show such a behaviour?  Give the reaction involved.

Name a reducing agent that may be used to obtain manganese from manganese dioxide.

Balance the following chemical equation:
MnO₂ + HCl \(\rightarrow\) MnCl₂ + Cl₂ + H₂O

Write the steps for balancing the chemical equation for the formation of ammonia by the combination of nitrogen and hydrogen.

2g ferrous sulphate crystals are heated in a dry boiling tube.
(i) List any two observations.
(ii) Name the type of chemical reaction taking place.
(iii) Write the chemical equation of the reaction.

On adding dilute HCl acid to copper oxide powder, the solution formed is blue-green. Predict the new compound formed which imparts a blue-green colour to the solution.

Name a major ore from which iron is extracted. Write chemical equations for the reactions that take place in the blast furnace for the extraction of iron from this ore.

(i) Name an important oxide ore of iron.
(ii) Describe the extraction of iron from those ore under the following heads:
(a) Reduction of the concentrated ore
(b) Diagram of the furnace used
(c) Chemical equations for the reactions involved

Give reasons for the following :
(i) Metals are regarded as electro-positive elements
(ii) When a piece of copper metal is added to a solution of zinc sulphate, no change takes place, but the blue colour of copper sulphate fades away when a piece of zinc is placed in its solution.
(iii) Articles made of alimunium do not corrode even though aluminium is an active metal.

From amongst the metals sodium, calcium, aluminium, copper and magnesium, name the metal.
(i) which reacts with water only on boiling and
(ii) another which does not react even with steam.

What is 'Plaster of Paris' chemically?  How is it obtained from gypsum?  Write the condition and chemical equation involved in its manufacture.

(a) Write the chemical name and formula of bleaching powder.
(b) Why does bleaching powder smell of chlorine when exposed to air?
(c) Write chemical equation to represent the action of dilute hydrochloric acid on bleaching powder

(i) Name the raw materials used in the manufacture of sodium carbonate by Solvay process.

(ii) How is the sodium hydrogen carbonate formed during Solvay process separated from a mixture of \(NH_4Cl\) and \(NaHCO_3\)?

(iii) How is sodium carbonate obtained from sodium hydrogen carbonate?

(a) What is the action on litmus of:

     (i) Dry ammonia gas

     (ii) Solution of ammonia gas in water

(b) State the observations you would make on adding ammonium hydroxide to aqueous solutions of:

What are the uses of washing soda?

Define the term decomposition reaction. Give one example each of thermal decomposition and electrolytic decomposition.

Write the steps for balancing the chemical equation for the formation of ammonia by the combination of nitrogen and hydrogen.

(a) Mention the four informations given by an equation.
(b) State the law of conservation of mass as applicable in a chemical reaction.

When a copper wire was left in silver nitrate solution for sometime, it was observed that the solution turned bluish green.
(i) Explain the observation.
(ii) Write the balanced chemical equation to represent the change taking place.

What changes can you make in your habits to become more environment friendly?

What would be the disadvantages of exploiting resources with short-term aims?

Suggest some approaches towards the conservation of forests.

Find out about the traditional systems of water harvesting/management in your region

What changes would you suggest in your home in order to be environment-friendly?

What are the problems caused by the non-biodegradable wastes that we generate?

If all the waste we generate is biodegradable, will this have no impact on the environment?

Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

We do not clean ponds or lakes, but an aquarium needs to be cleaned. Why?

Why energy of herbivores never come back to the autotrophs?

A person has normal vision, but he cannot distinguish between red-green colour. Why?

Mention few important features of visual system of a person?

Draw ray diagram each showing (i)myopic eye and  (ii) hypermetropic eye.

Why do we see a rainbow in the sky only after rainfall?

Why is the colour of the clear sky blue?

Define the principal focus of a concave mirror .

Why do we prefer a convex mirror as a rear view mirror in vehicles?

Find the focal length of a convex mirror whose radius of curvature is 32cm.

The refractive index of diamond is 2.42.What is the meaning of this statement?

Define 1 dioptre of power of a lens

Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?

How is the equal genetic contribution of male and female parents ensured in the progeny?

Mala is four-month pregnant and is worried whether the child is male or female. One day she reads an advertisement regarding a medicine which of taken for 3 months results in birth of male child. What should she do?
(a) Get the medicine and take it regularly.
(b) Visit a doctor and discuss the problem with him/her.
(c) What, in your opinion, are the chances of having a male child?

After reading about mendel's experiment on sweat pea Kala wanted to repeat the same in his kitchen garden. She bought sweet pea seeds and sowed them. After few months when the plants started flowering she observed that all the plants were tall.
(a) Why all plants were tall?
(b) Under which condition she could have observed both tall and dwarf plants?
(c) If she collects seeds from her garden and sows them, what type of plants she is expected to get? 

A new born has an XX pair of chromosomes. What is the sex of the new born baby?

If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?

What are the functions performed by the testis in human beings?

Why does menstruation occur?

Draw a labelled diagram of the longitudinal section of a flower.

Besides gallium, which other elements have since been discovered that were left by Mendeleev in his Periodic Table? (any two)

What were the criteria used by Mendeleev in creating his Periodic Table?

In the Modern Periodic Table, which are the metals among the first ten elements?

(a) What property do all elements in the same column of the Periodic Table as boron have in common?
(b) What property do all elements in the same column of the Periodic Table as fluorine have in common?

Nitrogen (atomic number 7) and phosphorus (atomic number 15) belong to group 15 of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?

A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

How would you distinguish experimentally between an alcohol and a carboxylic acid?

What will be the formula and electron dot structure of cyclopentane?

Explain the formation of scum when hard water is treated with soap.

Draw the electron dot structure of ethyne and also draw its structural formula.

What is a good fuel?

If you should use any source of energy for heating your food which one would you use and why?

What are the disadvantages of fossil fuels?

List four limitations of the energy-obtained from oceans.

Write three advantages of nuclear energy.

List the properties of magnetic lines of force.

Why don’t two magnetic field lines intersect each other?

State Fleming's Left hand Rule.

On what principle does electric motor work?

An electric oven of 2kW power rating is operated in a domestic electric circuit (220 v) that has a current rating of 5 A. What result do you expect ? Explain.

Define the unit of current.

Calculate the number of electrons constituting one coulomb of charge.

Will current flow more easily through a thick wire or a thin wire of the same material, when connected to the same source? Why?

An electric lamp of 100 \(\Omega \), a toaster of 50 \(\Omega \), and a water filter of resistance 500 \(\Omega \) are connected in parallel to a 220 V source. What is the resistance of an electric iron connected to the same source that takes as much current as all the three appliances, and what is the current through it?

An electric motor takes 5 A from a 220 V line. Determine the power of the motor and energy consumed in 2 h.

What is the difference between a reflex action and walking?

What is the role of the brain in reflex action?

What are plant hormones?

How do auxins promote the growth of a tendril around a support?

Why are some patients of diabetes treated by giving injections of insulin?

What are the components of the transport system in highly organised plants?

What is the function of digestive enzymes?

What are the methods used by plants to get rid of excretory products?

How the process of digestion will be affected if the bile ducts get blocked?

Two green plants are kept separately in oxygen free containers, one in the dark and the other in continuous light.Which one will live longer? Give reasons.

Explain the meanings of malleable and ductile.

What would you observe when zinc is added to a solution of Iron (II) sulphate? Write the chemical reaction that takes place.

What chemical process is used for obtaining a metal from its oxide?

What are amphoteric oxides? Give two examples of amphoteric oxides.

How is the concentration of hydronium ions H₃O⁺ affected when a solution of an acid is diluted?

How is the concentration of hydroxide ions (OH^-) affected when excess base is dissolved in a solution of sodium hydroxide?

Write an equation to show the reaction between plaster of paris and water.

Write word equations and then balanced equations for the reaction taking place when
(a) dilute sulphuric acid reacts with zinc granules.
(b) dilute hydrochloric acid reacts with magnesium ribbon
(c) dilute sulphuric acid reacts with aluminium powder
(d) dilute hydrochloric acid reacts with iron filings.

A milkman adds a very small amount of baking soda to fresh milk.
(i) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(ii) Why does this milk take a long time to set as curd?

Why should a magnesium ribbon be cleaned before burning in air?

Why is the amount of gas collected in one of the test tubes (electrolysis of water) double of the amount collected in the other? Name this gas.

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

Balance the following chemical equations.
(a) HNO₃ + Ca(OH)₂ \(\rightarrow\) Ca(NO₃)₂ + H₂O
(b) NaOH + H₂SO₄ \(\rightarrow\) Na₂SO₄ + H₂O
(c) NaCl + AgNO₃ \(\rightarrow\) AgCl + NaNO₃
(d) BaCl₂ + H₂SO₄ \(\rightarrow\) BaSO₄ + HCl

Write the balanced chemical equations for the following reactions.
(a) Calcium hydroxide + Carbon dioxide \(\rightarrow\) Calcium carbonate + Water
(b) Zinc + silver nitrate \(\rightarrow\) Zinc nitrate + Silver
(c) Aluminium + Copper chloride \(\rightarrow\) Aluminium chloride + Copper
(d) Barium chloride + Potassium Sulphate \(\rightarrow\) Barium sulphate + Potassium chloride

From the list given below pick the item that is not a natural resource

The main cause for abundant coliform bacteria in the river Ganga is

A successful forest conservation strategy should involve

Expand the abbreviation GAP

Select the incorrect statement

Which of the following groups contain only biodegradable items?

Which of the following constitute a food-chain?

Which of the following are environment-friendly practices?

An ecosystem includes

Accumulation of non-biodegradable pesticides in the food chain in increasing amount at each higher trophic level is known as

The human eye can focus objects at different distances by adjusting the focal length of the eye lens. This is due to

The human eye forms the image of an object at its

The least distance of distinct vision for a young adult with normal vision is about

The change in focal length of eye lens is caused by action of

A person cannot see distinctly objects kept beyond 2m.This defect can be corrected by using a lens of power

Which one of the following materials cannot be used to make a lens?

Where should an object be placed in front of a convex lens to get a real image of the size of the object?

Which of the following can make a parallel beam of light when light from a point source is incident on it?

Under which of the following conditions a concave mirror can form an image larger than the actual object?

Rays from Sun converge at a point 15 cm in front of a concave mirror. Where an object should be placed so that size of its image is equal to the size of the object? 

A mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as

Two pink coloured flowers on crossing resulted in 1 red, 2 pink and 1 white flower progeny. The nature of the cross will be

If a round, green seeded pea plant (RR yy) is crossed with wrinkled, yellow seeded pea plant, (rr YY) the seeds produced in FI generation are

The maleness of a child is determined by

A basket of vegetables contains carrot, potato, radish and tomato. Which of them represent the correct homologous structures?

Asexual reproduction takes place through budding in

Which of the following is not a part of the female reproductive system in human beings?

In a flower, the parts that produce male and female gametes (germ cells) are

Characters transmitted from parents to offspring are present in

A feature of reproduction that is common Amoeba, Spirogyra and Yeast is that

Element X forms a chloride with the formula XCl₂ , which is a solid a high melting point. X would most likely be in the same group of the Periodic Table as :

Which of the following statements about the Modern Periodic Table is correct:

Which of the following is the outermost shell for elements of period 2? 

Which one of the following elements exhibit maximum number of valence electrons?

Arrange the following elements in the order of their decreasing metallic character: Na, Si, Cl, Mg, Al

Ethane, with the molecular formula C₂H₆ has

Butanone is a four-carbon compound with the functional group

A molecule of ammonia (NH₃) has

Oils on treating with hydrogen in the presence of palladium or nickel catalyst form fats. This is an example of

Which of the following does not belong to the same homologous series?

A solar water heater cannot be used to get hot water on

Which of the following is not an example of a bio-mass energy source?

Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun's energy?

Acid rain happen because

Fuel used in thermal power plant is 

The magnetic field inside a long straight current carrying solenoid

Which of the following correctly describes the magnetic field near a long straight wire ?

The phenomenon of electromagnetic induction is 

The essential difference between an AC generator and a DC generator is that

At the time of short circuit, the current in the circuit

Electrical resistivity of a given metallic wire depends upon

If the current through a resistor is increased by 100% (assume that temperature remains unchanged), the increase in power dissipated will be

In an electrical circuit two resistors of 2\(\Omega \) and 4\(\Omega \) respectively are connected in series to a 6 V battery. The heat dissipated by the 4\(\Omega \) resistor in 5s will be

An electric kettle consumes 1 Kw of electric power when operated at 220 V. A fuse wire of what rating must be used for it?

Unit of electric power may also be expressed as

Which of the following is a plant hormone?

The brain is responsible for

Which is the correct sequence of the components of a reflex arc?

Which of the following statements are true about the brain?
(i) The main thinking part of brain is hind brain
(ii) Centres of hearing, smell, memory, sight, etc. are located in forebrain.
(iii) Involuntary actions like salivation, vomiting, blood pressure are controlled by the medulla in the hind brain
(iv) Cerebellum does not control posture and balance of the body

The movement of shoot towards light is

The kidneys in human beings are a part of the system for

The autotrophic mode of nutrition requires

In which of the following groups of organisms, food material is broken down outside the body and absorbed?

Which is the correct sequence of parts in human alimentary canal?

In salivary amylase is lacking in the saliva which of the following events in the mouth cavity will be affected?

Which of the following pairs will give displacement reactions?

An element reacts with oxygen to give a compound with a high melting point. This compound is also suitable in water. The element is likely to be

The ability of metals to be drawn into thin wire is known as

An element X forms an oxide which turns red litmus blue. Identify whether X is a metal or non-metal

Name a non-metal which is lustrous and a metal which is non-lustrous. 

A solution turns red litmus blue; its pH is likely to be?

What happens when a solution of an acid is mixed with a solution of a base in a test tube?

(a) The temperature of the solution increases

(b) The temperature of the solution decreases

(c) The temperatures of the solution remains the same

(d) Salt formation takes place

Which of the following salts does not contain water of crystallisation?

Which of the following is not a physical change?

Which of the following statements about the given reaction are correct?
3Fe(s) + 4H₂O(g) \(\rightarrow\) Fe₃O₄(s) + 4H₂(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent

Which of the following gases can be used for storage of fresh sample of an oil for a long time?

Name and state the law which is kept in mind while we balance a chemical equation.

State one basic difference between a physical change and a chemical change.

The unit of specific resistance is

1 kilowatt hour (kWh) is equal to

The commonly used safety fuse wire is made of

Electrical resistivity of a given metallic wire depends upon

A current of 1 A is drawn by a filament of an electric bulb. Number of electrons passing through a cross section of the filament in 16 seconds would be roughly

Ethane, with the molecular formula C₂H₆ has

Butanone is a four-carbon compound with the functional group

While cooking, if the bottom of the vessel is getting blackened on the outside, it means that

Carbon exists in the atmosphere in the form of

Which of the following statements are usually correct for carbon compounds? These
i) are good conductors of electricity
ii) are poor conductors of electricity
iii) have strong forces of attraction between their molecules
iv) do not have strong forces of attraction between their molecules

A solar water heater cannot be used to get hot water on

Which of the following is not an example of a bio-mass energy source?

Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun's energy?

Acid rain happen because

Fuel used in thermal power plant is 

The magnetic field inside a long straight current carrying solenoid

Which of the following property of a proton can change while it moves freely in a magnetic field ?

The strength of magnetic field inside a long current carrying straight solenoid is 

To convert an AC generator into DC generator

The most important safety method used for protecting home appliances from short circuiting or overloading is