Define a chemical reaction. Which observation help you to determine whether a chemical reaction has taken place?

3

(a)

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

3

(a)

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

3

(a)

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

3

(a)

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.

3

(a)

2 g 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.

3

(a)

(a) In the following reactions, name the reactants, which undergo 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.

3

(a)

(a) Write chemical equations.
(i) When carbon dioxide gas is passed through lime water.
(ii)When excess of carbon dioxide gas is passed through lime water.
(b) List two natural forms of calcium carbonate.

3

(a)

Identify the type of each of the following reactions. Also write balanced chemical equation for each.
(i) The reaction mixture becomes warm.
(ii) An insoluble substance is formed.

3

(a)

(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.

3

(a)

What happens when:
(i) Dilute hydrochloric acid is added to solid sodium carbonate.
(ii) Quicklime is treated with water.
(iii) Sodium chloride solution is added to lead nitrate solution.
Also write the chemical equation in each case.

3

(a)

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.

3

(a)

Complete and balance the following chemical equations:
(i) CaCO₃ + HCl
(ii) Al + HCl
(iii) MnO₂ + HCI

3

(a)