Dilute sulphuric acid is added to sodium sulphite. The following observations are noticed:

P — A gas with a suffocating smell is evolved which turns lime water milky.

Q — A foul smelling gas is evolved which turns lead acetate solution black.

R — A gas is evolved which decolourises pink KMnO₄

Which of the following is true?

1. Only P
2. Only Q
3. Only R
4. Both P and R

A compound X consists of molecules. Which of the following properties will be shown by X?

P — The boiling point of X is low.

Q — The compound X is soluble in water.

R — The aqueous solution of X does not conduct electricity.

1. Only P
2. Only Q
3. Only R
4. Both P and R

Assertion (A): SO₂ and CO₂ can be distinguished by lime water.

Reason (R): Both turn lime water milky.

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

Assertion (A): On passing H₂S through lead nitrate solution, a black precipitate is formed.

Reason (R): Lead nitrate reacts with H₂S to form a black precipitate of PbS.

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