Assertion (A): Burning of Natural gas is an endothermic process.

Reason (R): Methane gas combines with oxygen to produce carbon dioxide and water.

1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, and 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): Sodium hydrogen carbonate is used as an ingredient in antacids.

Reason (R): NaHCO₃ is a mild non-corrosive basic salt.

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

Which one of the following structures correctly depicts the compound CaCl₂?

The pair(s) which will show displacement reaction is/are

(i) NaCl solution and copper metal

(ii) AgNO₃ solution and copper metal

(iii) Al₂(SO₄)₃ solution and magnesium metal

(iv) ZnSO₄ solution and iron metal

1. (ii) only
2. (ii) and (iii)
3. (iii) and (iv)
4. (i) and (ii)