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

1

(a)

Heat, light and electricity.

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

1

(a)

(a) According to Arrhenius theory, acids are substances that produce \(H^+\) ions when mixed with water.  On the other hand, based are substances that produce \(OH^-\) ions when mixed with water.
(b) \(NH_4OH\) is a weak base and HCl is a strong acid.

1. Name the hormone secreted by thyroid gland.

   2

   (a)

   Thyroxine.

2. 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.

   2

   (a)

   The amount of heat produced in burning the unit mass of a fuel completely is known as the calorific value of that fuel. It is determined with the help of Bomb Calorimeter.
   Arrangement of the fuels in a decreasing order of their calorific values.
   LPG > Kerosene > Coal

1. 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.

   2

   (a)

   Atomic mass of Br = 35.5 + 126.9 / 2
                          = 162.4 / 2 = 81.2

2. In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a better body design? Why or why not?

   2

   (a)

   Evolution shows that body design changed from simple to complex. Hence, bacteria has the simplest body design and chimpanzee has the most complex and better body design

1. Why is it necessary to conserve our environment?

   3

   (a)

   It is necessary to conserve our environment to prevent depletion of natural resources and environmental damage, thereby sustaining life.

2. Why should biodegradable wastes be discarded in two separate dustbins?

   3

   (a)

   Biodegradable and non-biodegradable wastes should be discarded in two separate dust-bins because biodegradable waste is decomposed by the micro-organisms to form simple harmless substances which can be used as manures for the plants (e.g. in the potted plants in our garden/terrace garden). Non-biodegradable waste cannot be broken down naturally.

1. Classify the following salts into acidic, basic and neutral- Potassium sulphate, ammonium chloride, sodium carbonate, sodium chloride.

   3

   (a)

2. Why silver jewellery turns dull after some-time?

   3

   (a)

1. (a) Draw a diagram of human respiratory system and label the following:
   (i) Part where air is filtered by fine hair and mucus.
   (ii) Part which terminates into balloon-like structures.
   (iii) Balloon-like structure where exchange of gases takes place.
   (iv) Part which separates chest cavity from abdominal cavity.
   (b) What is common for Cuscuta, ticks and leeches?

   3

   (a)

2. With the help of a circuit diagram, derive the equivalent resistance of two resistances connected in series and in parallel.

   3

   (a)

1. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

   5

   (a)

2. Give any two advantages of construction dam.

   5

   (a)

1. (a) Name the chief ore of iron. Write its formula.
   (b) How is an iron ore concentrated? Describe it briefly.
   (c) Draw a labelled diagram of the blast furnace used in the extraction of iron from its concentrated ore.

   5

   (a)

2. How are oxygen and carbon dioxide transported in human beings? How are lungs designed to maximize the area for exchange of gases?

   5

   (a)

1. Draw a diagram of human brain and label on it the following of its parts:
   (i) Cerebrum
   (ii) Meninges
   (iii) Medulla Oblongata
   (iv) Cerebellum

   5

   (a)

2. Distinguish between permanent magnet and electromagnet.

   5

   (a)

1. What are the major parts of the brain? Mention the functions of different parts.

   2

   (a)

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

   2

   (a)

1. 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?

   2

   (a)

2. State the reason why carbon can neither form C⁴⁺ cations for C^4- anions, but forms covalent compounds. Also state reasons to explain why covalent compounds:
   (a) are bad conductors of electricity?
   (b) have low melting and boiling points

   2

   (a)

1. Give an account of the process adopted by Mendeleev for the classification of elements. How did he arrive at "Periodic Law"?

   2

   (a)

2. What is meant by speciation? List four factors which could lead to speciation. Which of these cannot be a major factor in the speciation of a self-pollinating plant species. Give reason to justify your answer.

   2

   (a)

A person can comfortably read a book, but finds difficult to read the number on a bus parked 5m away from him. Name the type of defect of vision he is suffering from. Which type of lens should he use in his spectacle to correct his vision?

2

(a)

Defect-Myopia or short-sightedness Correction-Concave lens

Describe an activity to draw the magnetic field lines around a coil carrying current.

3

(a)

Why are solar heating devices painted black? Name two such devices and state two limitations of these.

3

(a)

Explain the hydrolysis of ester and sodium hydroxide.

3

(a)

The yeast cells fail to multiply in water, but multiply rapidly in sugar solution. Why?

3

(a)

Explain dihybrid cross.

3

(a)

The image formed by a spherical mirror is real, inverted and is of magnification -2. If the image is at a distance of 30 cm from the mirror, where is the object place? Find the focal length of the mirror. List two characteristics of the image formed if the object is moved 10 cm towards the mirror.

3

(a)

Draw a ray diagram showing through a prism when a narrow beam of white light is incident on one of its refracting surfaces. Also indicate the order of the colours of the spectrum obtained.

3

(a)

(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.

5

(a)

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.

5

(a)

Draw the diagram of alimentary canal of man and label the following parts.
Mouth, Oesophagus, Stomach, Intestine

5

(a)

How does refraction take place in the atmosphere?Why do stars twinkle but not the planets?

2

(a)

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

2

(a)

What is the importance of forest as a resource?

2

(a)