Statement-1 : `Delta H_(f)^(@)` is zero for oxygen `(O_(2))`.
And
Statement-2 : `Delta H_(f)^(@)` for all the elements at S.T.P. is zero.

Options

A. Statement-1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement-1
B. Statement-1 is True, Statement-2 is True, Statement-2 is Not a correct explanation for Statement-1
C. Statement-1 is True, Statement-2 is False
D. Statement-1 is False, Statement-2 is True

Answer

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

### Step 1: Evaluate Statement 1
**Statement 1**: `ΔH_f^(@)` is zero for oxygen `(O_2)`.

- The enthalpy of formation (`ΔH_f`) refers to the change in enthalpy when one mole of a compound is formed from its elements in their standard states.
- For any element in its standard state, the enthalpy of formation is defined to be zero.
- Oxygen in its standard state is `O_2` (gaseous diatomic oxygen).
- Therefore, the enthalpy of formation for `O_2` is indeed zero.

**Conclusion for Statement 1**: True.

### Step 2: Evaluate Statement 2
**Statement 2**: `ΔH_f^(@)` for all the elements at S.T.P. is zero.

- The statement claims that the enthalpy of formation for all elements at standard temperature and pressure (S.T.P.) is zero.
- However, the enthalpy of formation is zero only for elements in their standard state.
- While many elements exist in their standard states at S.T.P., not all elements are in their elemental form at S.T.P.
- For example, carbon can exist as graphite or diamond, and the enthalpy of formation for these forms will not be zero.
- Therefore, the statement is misleading because it implies that all forms of elements at S.T.P. have a zero enthalpy of formation, which is not accurate.

**Conclusion for Statement 2**: False.

### Final Conclusion
- Statement 1 is true.
- Statement 2 is false.

Thus, the correct option is that Statement 1 is true and Statement 2 is false.