Assertion: The enthalpy of formation of gaseous oxygen molecules at `298K` and under1 atm is zero.
Reason: The entropy of formation of gaseous oxygen molecules under the same condition is zero.

Options

A. If both (A) and (R ) are correct, and (R ) is the correct explanation for (A).
B. If the both (A) and (R ) are correct, but(R ) is not a correct explanation for (A).
C. If (A) is correct, but (R ) is incorrect.
D. If (A) is incorrect, but (R ) is correct.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understanding the Assertion
The assertion states that the enthalpy of formation of gaseous oxygen molecules (O2) at 298 K and under 1 atm is zero.

- **Enthalpy of Formation**: The enthalpy of formation (ΔH_f) of a substance is defined as the change in enthalpy when one mole of a compound is formed from its elements in their standard states. For oxygen gas (O2), which is the standard state of oxygen at 298 K and 1 atm, the enthalpy of formation is indeed defined as zero because it is in its elemental form.

### Step 2: Understanding the Reason
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