When a certain amount of ethylene was combusted, $6226 \mathrm{kJ}$ heat was evolved. If heat of combustion of ethylene is$1411 \mathrm{kJ}$, determine the volume of ${\mathrm{O}}_2$ (at $\mathrm{NTP}$) that entered into the reaction.

Given the following reactions:

I: ${\mathrm{N}}_2\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)⟶2{\mathrm{NO}}_2\left(\mathrm{g}\right), {\mathrm{\Delta H}}_{\mathrm{I}}=16.18 \mathrm{kcal}$

II: ${\mathrm{N}}_2\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)⟶{\mathrm{N}}_2{\mathrm{O}}_4\left(\mathrm{g}\right), {\mathrm{\Delta H}}_{\mathrm{II}}=2.31 \mathrm{kcal}$

Which amongst ${\mathrm{NO}}_2\left(\mathrm{g}\right)$ and ${\mathrm{N}}_2{\mathrm{O}}_4\left(\mathrm{g}\right)$ is more stable?

Substance ${\mathrm{A}}_2\mathrm{B}\left(\mathrm{g}\right)$ can undergo decomposition to form two sets of products:

If the molar ratio of ${\mathrm{A}}_2\left(\mathrm{g}\right)$ to $\mathrm{A}\left(\mathrm{g}\right)$ is $5:3$ in a set of product gases, determine then the energy involved in the decomposition of $1$mole of ${\mathrm{A}}_2\mathrm{B}$.

For the hypothetical reaction:

${\mathrm{A}}_2\left(\mathrm{g}\right)+{\mathrm{B}}_2\left(\mathrm{g}\right)\rightleftharpoons 2\mathrm{AB}\left(\mathrm{g}\right)$

If ${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{G}}^{\underset{-}{\mathrm{o}}}$ and ${\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{S}}^{\underset{-}{\mathrm{o}}}$ are $20 \mathrm{kJ}/\mathrm{mol}$ and $-20 {\mathrm{JK}}^{-1} {\mathrm{mol}}^{-1}$, respectively at $200 \mathrm{K}. {\mathrm{\Delta }}_{\mathrm{r}}{\mathrm{C}}_{\mathrm{p}}$ is $20 {\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$ then determine ${\mathrm{\Delta }}_{\mathrm{r}}\mathrm{H}°$ at $400 \mathrm{K}$.

A molecule whose molar specific heat at high temperature, assuming ideal behaviour, is $9\mathrm{R}$ is: