STATEMENT-1 : The Heat absorbed during the isothermal expansion of an ideal gas against vacuum is zero.
STATEMENT-2 : The volume occupied by the molecules of an ideal gas is zero.

Options

A. If both the statement are TRUE and STATEMENT-2 is the correct explanation of STATEMENT-1
B. If both the statement are TRUE but STATEMENT-2 is NOT the correct explanation of STATEMENT-1
C. If STATEMENT-1 is TRUE and STATEMENT-2 is FALSE
D. If STATEMENT-1 is FALSE and STATEMENT-2 is TRUE

Answer

To solve the question, we need to analyze both statements and determine their validity and relationship.

### Step-by-Step Solution:

**Step 1: Analyze Statement 1**
- **Statement 1**: "The heat absorbed during the isothermal expansion of an ideal gas against vacuum is zero."
- In an isothermal process, the temperature remains constant. When an ideal gas expands against a vacuum, there is no external pressure opposing the expansion.
- Since work done (W) against vacuum is zero (W = -P_external * ΔV, where P_external = 0), we can conclude that no work is done on the surroundings.
- According to the first law of thermodynamics: ΔU = Q + W, where ΔU is the change in internal energy, Q is the heat absorbed, and W is the work done.
- For an ideal gas undergoing isothermal expansion, ΔU = 0 (since temperature is constant). Therefore, Q = -W = 0.
- Thus, Statement 1 is **true**.

**Step 2: Analyze Statement 2**
- **Statement 2**: "The volume occupied by the molecules of an ideal gas is zero."
- The assumption of an ideal gas is that the volume occupied by the gas molecules themselves is negligible compared to the volume of the container.
- This means that while the gas occupies a certain volume, the actual volume taken up by the gas molecules is considered to be zero for the purpose of calculations.
- Thus, Statement 2 is also **true**.

**Step 3: Determine the Relationship Between Statements**
- Both statements are true, but they are independent of each other. Statement 1 refers to the heat absorbed during isothermal expansion, while Statement 2 refers to the volume occupied by gas molecules in the ideal gas model.
- Therefore, there is no direct explanation of Statement 1 by Statement 2.

**Conclusion:**
- Both statements are true, but Statement 2 does not explain Statement 1. The correct answer is that both statements are true, but Statement 2 is not the explanation for Statement 1.

### Final Answer:
Both Statement 1 and Statement 2 are true, but Statement 2 is not the explanation for Statement 1.

---