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.

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

A rectangular coil of copper wire is rotated in a magnetic field. The direction of the induced current changes once in each

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

\(CH_3- {CH_2 }-OH \xrightarrow [ ]{ Alkaline \ KMnO_4+Heat } CH_3- COOH\)
In the above given reaction, alkaline KMnO ₄ acts as 

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

Write a balanced chemical equation:
\({ FeSO }_{ 4 }\overset { Heat }{ \rightarrow } { Fe }_{ 2 }{ O }_{ 3 }(s)+S{ O }_{ 2 }(g)+{ SO }_{ 3 }(g)\)

Silver articles develop black coating and copper articles develop green coating. Which chemical phenomenon is responsible for this coating?

Define metals.

Name the metal which has very low melting point and can melt with heat of your palm?

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

How do autotrophs obtain CO₂ and N₂ to make their food?

What are life processes?

Which are the most common chemical reaction in a body?

What are cranial nerves?

Name the part of brain in which hypothalamus is located.

What is synapse?

What is meant by the statement, "Potential difference between points A and B in an electric field is 1 volt"?

What is a voltmeter?

What is the advantage of the third wire of earth connection in domestic electric appliances?

What does an electric current carrying wire behaves like?

Name the rule used to determine the direction of induced current.

What is a compass needle?

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

What are the applications of solar cells?

Which is the ultimate source of energy?

What is the difference in the molecular formula of any two consecutive members of a homologous series of organic compounds?

State two characteristic features of carbon which when put together give rise to large number of carbon compounds.

Write the name and formula of the first member of the carbon compounds having functional group -COOH.

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.

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.

State modern periodic law of classification of elements.

Name the term used to indicate the development of unpleasant smell and taste in fat and oil containing foods due to aerial oxidation.

Name the following:

(a) An indicator which is red in acidic medium but turns blue in basic medium.

(b) An indicator which is pink in basic medium but turns colourless in acidic medium.

A non-metal X exists in two different forms Y and Z, Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y and Z.

What will happen if platelets were absent in the blood?

What is the function of receptors in our body? Think of situations where receptors do not work properly. What problems are likely to arise?

How would you calculate the heat produced when 96,000 C of charge is transferred in an hour through a potential difference of 50V?

Under what conditions permanent electromagnet is obtained if a current carrying solenoid is used? Support your answer with the help of a labelled circuit diagram.

List any four reasons why we need to look for alternate source of energy.

How will carbon achieve its stability?

If an element A is placed in group 14, what will be the formula and the nature of bonding of its chloride?

(a) In the following reactions, name the reactants, which undergoes oxidation and reduction:
(i) CuO(s) + H₂(g) \(\longrightarrow \) Cu(s) + H₂O(g)
(ii)CuO(s) + Zn(s) \(\longrightarrow \) ZnO(s) + Cu(s)
(b) State one industrial application of reduction.

(i) Solution of a substance 'X' is used for testing carbon dioxide. Write the equation of the reaction of 'X' with carbon dioxide.
(ii) How is 'X' obtained? Write chemical equation.

(a) State the relation between hydrogen ion concentration of an aqueous solution and its pH.

(b) The pH of an aqueous solution decreases from 3 to 2.  Calculate how many times the hydrogen ion concentration of the solution will change.

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.

List three properties of sodium in which it differs from the general physical properties of most metals.

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

What is 'translocation'? Why is it essential for plants?Where in plants are the following synthesized:
(i)Sugar  (ii)Hormones

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

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

(a) Distinguish between the terms "overloading and short circuiting" as used in domestic circuits.
(b) Why are the coils of electric toasters made of an alloy rather than a pure metal?

Differentiate between ammeter and voltmeter.

Distinguish between an electric motor and generator?

Distinguish between permanent magnet and electromagnet.

(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'.

You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO₃, ZnCl₂ and H₂O. In which of the above containers theses solutions can be kept?

(i) Define pH scale. Draw a figure showing a variation of pH with the change in concentration of H⁺(aq) and OH^- (aq) ions.
(ii) Mention the range of pH of the acidic solution, basic solution, and neutral solution respectively.

(a) What is corrosion of metals? Name one metal which does not corrode and one which corrodes on being kept in atmosphere.
(b) How will you show that the rusting of iron needs oxygen and moisture at the same time?

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

How does chemical coordination take place in animals?

Find out the following in the electric circuit given in figure
(a) Effective resistance of two 8\(\Omega\) resistors in the combination
(b) Current flowing through 4\(\Omega\) resistor. 
(c) Potential difference across 4\(\Omega\) resistance
(d) Power dissipated in 4\(\Omega\) resistor.
(e) Difference in ammeter readings, if any.

(a) Describe with diagram an experiment to show that a force is exerted on a current-carrying conductor when placed perpendicular in a magnetic field.
(b) State the rule to find the direction of the force exerted on a current-carrying conductor in a magnetic field.

What is biomass? Explain the principle working of a biogas plant using a labelled schematic diagram.

Draw the possible isomers of the compound it molecular formula C₃H₆O and also give their electron dot structures.

Complete the following cross word puzzle shown in the below Figure
Across:
(1) An element with atomic number 12.
(3) Metal used in making cans and member of Group 14.
(4) A lustrous non-metal which has 7 electrons in its outermost shell.
Down:
(2) Highly reactive and soft metal which imparts yellow colour when subjected to flame and is kept in kerosene.
(5) The first element of second Period.
(6) An element which is used in making fluorescent bulbs and is second member of Group 18 in the Modern Periodic Table.
(7) A radioactive element which is the last member of halogen family.
(8) Metal which is an important constituent of steel and forms' rust when exposed to moist air.
(9) The first metalloid in Modern Periodic Table whose fibres are used in making bullet-proof vests.