At $550\,^{\circ}\text{C}$, nitrogen dioxide reacts with unburnt hydrocarbon fragments such as $\text{CH}_3\cdot$ inside the catalytic converter of a motor vehicle. $4\text{CH}_3\cdot + 7\text{NO}_2 \rightarrow 3\tfrac{1}{2}\text{N}_2 + 4\text{CO}_2 + 6\text{H}_2\text{O}$ The table below shows the kinds of energy change for this reaction together with possible explanations for these changes. Which row shows the energy change for this reaction and the explanation for it?
- Aendothermic; chemical energy is converted to heat energy
- Bendothermic; the $\text{N}\equiv\text{N}$ bond energy is very high
- Cexothermic; $\text{CO}_2$ and $\text{H}_2\text{O}$ have large negative $\Delta H_f^{\circ}$ values
- Dexothermic; double bonds are broken in $\text{NO}_2$