English Medium कक्षा १० - CBSE Question Bank Solutions for Science

The chemical reaction between two substances is characterised by a change in colour from orange to green. These two substances are most likely to be:
(a) potassium dichromate solution and sulphur dioxide
(b) potassium permanganate solution and sulphur dioxide
(c) potassium permanganate solution  and lemon juice
(d) potassium dichromate solution and carbon dioxide.

The chemical reaction between quicklime and water is characterised by:
(a) evolution of hydrogen gas
(b) formation of slaked lime precipitate
(c) change in temperature of mixture
(d) change in colour of the product

Which of the following is not an endothermic reaction?

(a) CaCO₃ → CaO  +  CO₂

(b) 2H₂O →2H₂ + O₂

(c) 6CO₂ + 6H₂O → C₆H₁₂O₆  +  6O₂

(d) C₆H₁₂O₆  + 6O₂ → 6CO₂  + 6H₂O

One of the following is an exothermic reaction. This is:
(a) electrolysis of water
(b) conversion of limestone into quicklime
(c) process of respiration
(d) process of photosynthesis

The chemical equations are balanced to satisfy one of the following laws in chemical reactions. This law is know as:
(a) law of conservation of momentum
(b) law of conservation of mass
(c) law of conservation of motion
(d) law of conservation of magnetism

When the solution of substance X is added to a solution of potassium iodide, then a yellow solid separates out from the solution.
(a) What do you think substance X is likely to be?
(b) Name the substance which the yellow solid consists of.
(c) Which characteristic of chemical reaction is illustrated by this example?
(d) Write a balanced chemical equation for the reaction which takes place. Mention the physical states of all the reactant and products involved in the chemical equation.

When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.
(a) What could be solid X? Write its chemical formula.
(b) What could be product Y? Write its chemical formula.
(c) What is the common name of the solution of Y which is used for testing carbon dioxide gas?
(d) Write chemical equation of the reaction which takes place on adding water to slid X.
(e) Which characteristic of chemical reactions is illustrated by this example?

When metal X is treated with a dilute acid Y, then a gas Z is evolved which burns readily by making a little explosion.
(a) Name any two metals which can behave like metal X.
(b) Name any two acids which can behave like acid Y.
(c) Name the gas Z.
(d) Is the gas Z lighter than or heavier than air?
(e) Is the reaction between metal X and dilute acid Y, exothermic or endothermic?
(f) By taking a specific example of metal X and dilute acid Y, write a balanced chemical equation for the reaction which takes place. Also indicate physical states of all the reactants and products.

A metal X forms a salt XSO₄. The salt XSO₄ forms a clear solution in water which reacts with sodium hydroxide solution to form a blue precipitate Y. Metal X is used in making electric wire and alloys like brass.
(a) What do you think metal X could be?
(b) Write the name, formula and colour of salt XSO₄.
(c) What is the blue precipitate Y?
(d) Write a chemical equation of the reaction which takes place when salt XSO₄ reacts with sodium hydroxide solution. Give the state symbols of all the reactants and products which occur in the above equation.

The metal M reacts vigorously with water to form a solution S and a gas G. The solution S turns red litmus to blue whereas gas G, which is lighter than air, burns with a pop sound. Metal M has a low melting point and it is used as a coolant in nuclear reactors.
(a) What is metal M?
(b) What is solution S? Is it acidic or alkaline?
(c) What is gas G?
(d) Write a balanced chemical equation for the reaction which takes place when metal M reacts with water.
(e) Is this reaction exothermic or endothermic?

When a mixture of gases X and Y is compressed to 300 atm pressure and then passed over a catalyst consisting of a mixture of zinc oxide and chromium oxide (heated to a temperature of 300°C), then an organic compounds Z having the molecular formula CH₄O is formed. X is a highly poisonous gas which is formed in appreciable amounts when a fuel burns in a limited supply of air; Y is a gas which can be made by the action of a dilute acid on an active metal; and Z is a liquid organic compound which can react with sodium metal to produce hydrogen gas.
(a) What are X, Y and Z?
(b) Write a balanced chemical equation of the reaction which takes place when X and Y combine to form Z. Indicate the conditions under which the reaction occurs.

Name the various types of chemical reactions.

Balance the following chemical equation:

Balance the following chemical equation:

Express the following facts in the form of a balanced chemical equation:
"When a strip of copper metal is placed in a solution of silver nitrate, metallic silver is precipitated and a solution containing copper nitrate is formed".

Write balanced chemical equation with state symbols for the following reaction:
Barium chloride solution reacts with sodium sulphate solution to give insoluble barium sulphate and a solution of sodium chloride.

What happens when silver nitrate solution is added to sodium chloride solution?
Write the equation for the reaction which takes place.

The removal of oxygen from a substance is called:
(a) oxidation
(b) corrosion
(c) reduction
(d) rancidity

A white precipitate can be obtained by adding dilute sulphuric acid to:
(a) CuSO₄ solution
(b) Nacl solution
(c) BaCl₂ solution
(d) Na₂SO₄ solution