The enthalpy of formation of hypothetical `MgCl` is `-125kJ mol^(-1)` and for `MgCl_(2)` is `-642 kJ mol^(-1)`. What is the enthalpy of the disproportionation of `MgCl`.

Options

A. `392 kJ mol^(-1)`
B. `-392 kJ mol^(-1)`
C. `-767 kJ mol^(-1)`
D. `-517 kJ mol^(-1)`

Explanation

To find the enthalpy of disproportionation of MgCl, we need to analyze the reactions involved and use the given enthalpy values for the formation of MgCl and MgCl2.

### Step-by-Step Solution:

1. **Identify the Reactions:**
- The formation of MgCl can be represented as:
\[
\text{Mg} + \frac{1}{2} \text{Cl}_2 \rightarrow \text{MgCl} \quad (\Delta H_1 = -125 \, \text{kJ/mol})
...