Which of the following equations corresponds to the definition of enthalpy of formation at `298K`?

Options

A. `C("graphite") +2H_(2)(g) +(1)/(2)O_(2)(l) rarr CH_(3) OH(g)`
B. `C("diamond") +2H_(2)(g)+(1)/(2)O_(2)(g) rarr CH_(3)OH(l)`
C. `2C("graphite") +4H_(2)(g) +O_(2)(g) rarr 2CH_(3)OH(l)`
D. `C("graphite") +2H_(2)(g) +(1)/(2)O_(2)(g) rarr CH_(3)OH(l)`

Explanation

To determine which equation corresponds to the definition of enthalpy of formation at 298 K, we need to understand what enthalpy of formation means. The enthalpy of formation (ΔH_f) of a compound is defined as the heat change that results when one mole of the compound is formed from its elements in their standard states at a specified temperature, typically 298 K (25 °C).

### Step-by-Step Solution:

1. **Identify the Standard States of Elements**:
- The standard state for carbon is graphite.
- The standard state for hydrogen is H₂ gas.
- The standard state for oxygen is O₂ gas.
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