Chemistry · THERMODYNAMICS

The stepwise bond dissociation enthalpies for methane are: \( \text{CH}_4(g) \rightarrow \text{CH}_3(g) + \text{H}(g) \); \( \Delta_{\text{bond}} H_1^\ominus = +427\text{ kJ mol}^{-1} \) \( \text{CH}_3(g) \rightarrow \text{CH}_2(g) + \text{H}(g) \); \( \Delta_{\text{bond}} H_2^\ominus = +439\text{ kJ mol}^{-1} \) \( \text{CH}_2(g) \rightarrow \text{CH}(g) + \text{H}(g) \); \( \Delta_{\text{bond}} H_3^\ominus = +452\text{ kJ mol}^{-1} \) \( \text{CH}(g) \rightarrow \text{C}(g) + \text{H}(g) \); \( \Delta_{\text{bond}} H_4^\ominus = +347\text{ kJ mol}^{-1} \) What is the mean \( \text{C}-\text{H} \) bond enthalpy in methane?

1. A
   \( 427.00\text{ kJ mol}^{-1} \)
2. B
   \( 416.25\text{ kJ mol}^{-1} \)
3. C
   \( 347.00\text{ kJ mol}^{-1} \)
4. D
   \( 1665.0\text{ kJ mol}^{-1} \)