Name the substance oxidised and the substance reduced, and also identify the oxidising agent and reducing agents in the following reaction:

(a) 3MnO₂ + 4Al → 3Mn + 2Al₂O₃

(b) Fe₂O₃ + 3CO → 2Fe + 3CO₂

(c) SO₂ + 2H₂S → 3S + 2H₂O (2015)

Write the balanced chemical equation for the following reaction: (2014)

(i) Phosphorus burns in chlorine to form phosphorus pentachloride.

(ii) Burning of natural gas.

(iii) The process of respiration.

(a) A substance X, an oxide of a metal, is used extensively in the cement industry. This element is found in our bones also. One treatment with water it forms a solution which turns red litmus blue.

Identity X and also write the chemical reaction involved.

(b) Choose a metal from the following metals which reacts only with hot water: Sodium, magnesium, iron.

Mention the products formed during the reaction. (2014)

(a) In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode?

(b) (i) What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube?

(ii) What type of reaction is this?

(iii) Write a balanced chemical equation to represent the above reaction. (2015)

(a) What happens when an aqueous solution of sodium sulphate reacts with an aqueous solution of barium chloride? State the physical conditions of reactants in which reaction between them will not take place. Write the balanced chemical equation for the reaction and also mention the type of reaction.

(b) What changes in the colour of iron nails and copper sulphate solution do you observe after keeping the iron nails in copper sulphate solution for about half an hour? (2015)