Chemistry · 2014
JEE Main · 12 April 2014, Shift 1 · Q40
The standard enthalpy of formation (Δ_f H^o_298) for methane, CH_4 is -74.9 kJ mol^-1. In order to calculate the average energy given out in the…
The standard enthalpy of formation $\displaystyle \left(\Delta_{\mathrm{f}} \mathrm{H}^{\mathrm{o}}{ }_{298}\right)$ for methane, $\displaystyle \mathrm{CH}_4$ is $\displaystyle -74.9 \mathrm{~kJ} \mathrm{~mol}^{-1}$. In order to calculate the average energy given out in the formation of a $\displaystyle \mathrm{C}-\mathrm{H}$ bond from this it is necessary to know which one of the following ?
Official answer
(3)
the dissociation energy of $\displaystyle \mathrm{H}_2$ and enthalpy of sublimation of carbon (graphite).
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JEE Main 2014 Chemistry question, with the answer from NTA’s final answer key. Where our answers come from.