Statement-1. Vapour pressure of liquid ammonia is more than that of water.
Statement-2. Molar mass of ammonia is less than that of water.

Options

A. Statement-1 is true, statement-2 is also true, statement-2 is correct explanation of statement-1
B. Statement-1 is true, statement-2 is also true, statement-2 is not correct explanation of statement-1
C. Statement-1 is true, statement-2 is true.
D. Statement-1 is false, statement-2 is true.

Explanation

To analyze the statements provided in the question, we will evaluate each statement step by step.

### Step 1: Analyze Statement-1
**Statement-1:** Vapour pressure of liquid ammonia is more than that of water.

- **Vapour Pressure and Hydrogen Bonding:** Vapour pressure is inversely related to the strength of hydrogen bonding in a liquid. The stronger the hydrogen bonding, the lower the vapour pressure.
- **Comparison of Hydrogen Bonding:**
- Water (H₂O) has a high degree of hydrogen bonding due to the high electronegativity of oxygen, which can form up to four hydrogen bonds with surrounding water molecules.
- Ammonia (NH₃) has hydrogen bonding as well, but the nitrogen atom is less electronegative than oxygen, resulting in weaker hydrogen bonds compared to water.

**Conclusion for Statement-1:** Since water has stronger hydrogen bonding than ammonia, it will have a lower vapour pressure. Therefore, the statement that the vapour pressure of liquid ammonia is more than that of water is **true**.

### Step 2: Analyze Statement-2
**Statement-2:** Molar mass of ammonia is less than that of water.

- **Calculate Molar Mass:**
- Molar mass of ammonia (NH₃): Nitrogen (N) has a molar mass of approximately 14 g/mol, and each hydrogen (H) has a molar mass of about 1 g/mol. Therefore, the molar mass of ammonia is:
\[ \text{Molar mass of NH₃} = 14 + (3 \times 1) = 17 \text{ g/mol} \]
- Molar mass of water (H₂O): Oxygen (O) has a molar mass of approximately 16 g/mol, and two hydrogens contribute:
\[ \text{Molar mass of H₂O} = 16 + (2 \times 1) = 18 \text{ g/mol} \]

**Conclusion for Statement-2:** Since the molar mass of ammonia (17 g/mol) is indeed less than that of water (18 g/mol), this statement is also **true**.

### Final Conclusion
Both statements are true:
- Statement-1 is true because the vapour pressure of ammonia is higher than that of water due to weaker hydrogen bonding.
- Statement-2 is true because the molar mass of ammonia is less than that of water.

However, the second statement does not provide a correct explanation for the first statement.