For which one of the following equation is `DeltaH_(reaction)^(@)` equal to `DeltaH_(f)^(@)` for the product ?

Options

A. `Xe(g) + 2F_2(g) to XeF_(4)(g)`
B. `2CO(g)+O_(2)(g) to 2CO_(2)(g)`
C. `N_(2)(g) + O_(3)(g) to N_(2)O_(3)(g)`
D. `CH_(4)(g) + 2Cl_(2)(g) to CH_(2)Cl_(2)(l) + 2HCl(g)`

Explanation

To determine for which of the following equations the standard enthalpy of reaction (ΔH_reaction^(@)) is equal to the standard enthalpy of formation (ΔH_f^(@)) for the product, we need to analyze the provided equations carefully.

### Step-by-Step Solution:

1. **Understand Enthalpy of Formation**:
- The standard enthalpy of formation (ΔH_f^(@)) is defined as the heat change that occurs when one mole of a compound is formed from its elements in their standard states (298 K and 1 bar pressure). For elements in their standard states, ΔH_f^(@) is zero.

2. **Analyze the First Reaction**:
- The first reaction is:
\[ \text{Xe (g)} + 2 \text{F}_2 (g) \rightarrow \text{XeF}_4 (g) \]
- Here, Xe and F2 are elements in their standard states. The reaction forms one mole of XeF4 from its elements.
- Therefore, ΔH_reaction^(@) = ΔH_f^(@) for XeF4. This reaction is valid.

3. **Analyze the Second Reaction**:
- The second reaction is:
\[ 2 \text{CO} (g) + \text{O}_2 (g) \rightarrow 2 \text{CO}_2 (g) \]
- This reaction represents the combustion of carbon monoxide. The enthalpy change here is the enthalpy of combustion, not formation. Hence, ΔH_reaction^(@) does not equal ΔH_f^(@) for CO2.

4. **Analyze the Third Reaction**:
- The third reaction is:
\[ 3 \text{O}_3 (g) \rightarrow 2 \text{O}_2 (g) \]
- Ozone (O3) is not in its standard state for oxygen. Therefore, this reaction does not represent the formation of O2 from its elements in standard states, making it invalid for our comparison.

5. **Analyze the Fourth Reaction**:
- The fourth reaction is:
\[ \text{CH}_4 (g) + 2 \text{O}_2 (g) \rightarrow \text{CO}_2 (g) + 2 \text{H}_2\text{O} (l) \]
- This reaction represents the combustion of methane. Similar to the second reaction, this is an enthalpy of combustion, not formation. Thus, ΔH_reaction^(@) does not equal ΔH_f^(@) for CO2 or H2O.

### Conclusion:
The only reaction for which ΔH_reaction^(@) is equal to ΔH_f^(@) for the product is the first reaction:
\[ \text{Xe (g)} + 2 \text{F}_2 (g) \rightarrow \text{XeF}_4 (g) \]

### Final Answer:
**The correct option is the first reaction.**