A compound P is heated in a test tube with sodium hydroxide solution. A red litmus paper held at the mouth of the test tube turns blue. Which of the following could compound P be?

1. zinc sulphate
2. copper sulphate
3. ferrous sulphate
4. ammonium sulphate

Assertion (A): Aqueous solution of potassium chloride can conduct electricity.

Reason (B): Conduction of electric current is due to the presence of free ions.

1. (A) is true and (R) is false.
2. (A) is false and (R) is true.
3. Both (A) and (R) are true and (R) is the correct explanation of (A).
4. Both (A) and (R) are true, but (R) is not the correct explanation of (A).

Four reactions are shown below in the diagram:

Which reactions produce water?

1. 1 and 2
2. 1 and 3
3. 3 and 4
4. 2 and 3

When compound X reacts with dilute sulphuric acid, it releases a gas that turns acidified potassium dichromate solution from orange to green. Which of the following could be compound X?

1. Lead nitrate
2. Copper carbonate
3. Sodium chloride
4. Potassium sulphite