The standard enthalpy of the formation of ${\mathrm{NH}}_3$ is $-46.0 \mathrm{kJ} {\mathrm{mol}}^{-1}$. If the enthalpy of the formation of ${\mathrm{H}}_2$ from its atoms is $-436 \mathrm{kJ} {\mathrm{mol}}^{-1}$ and that of ${\mathrm{N}}_2$ is $-712 \mathrm{kJ} {\mathrm{mol}}^{-1}$, the average bond enthalpy of $\mathrm{N}-\mathrm{H}$ bond in ${\mathrm{NH}}_3$ is:

On the basis of the following thermochemical data:

${\mathrm{\Delta H}}_{\mathrm{f}}°\left({\mathrm{H}}_{\mathrm{aq}}^{+}\right)=0$

$\begin{array}{l}{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{H}}^{+}\left(\mathrm{aq}\right)+{\mathrm{OH}}^{-}\left(\mathrm{aq}\right); \mathrm{\Delta H}°=57.32\mathrm{kJ}\\ {\mathrm{H}}_2\left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right); \mathrm{\Delta H}°=-286.20\mathrm{kJ}\end{array}$

The value of the enthalpy of formation of ${\mathrm{OH}}^{-}$ ions at $25°\mathrm{C}$ is:

Based on the following thermochemical equation:

${\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right) + \mathrm{C} \left(\mathrm{s}\right) =\mathrm{CO} \left(\mathrm{g}\right) + {\mathrm{H}}_{2 }\left(\mathrm{g}\right) ; ∆\mathrm{H} = 131 \mathrm{kJ}$

$\mathrm{CO}\left(\mathrm{g}\right) +\frac{1}{2} {\mathrm{O}}_2 \left(\mathrm{g}\right) ={\mathrm{CO}}_2\left(\mathrm{g}\right) ; ∆\mathrm{H} =- 282 \mathrm{kJ}$

${\mathrm{H}}_2\left(\mathrm{g}\right) +\frac{1}{2} {\mathrm{O}}_2 \left(\mathrm{g}\right) ={\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right) ; ∆\mathrm{H} = -242 \mathrm{kJ}$

$\mathrm{C}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)={\mathrm{CO}}_2\left(\mathrm{g}\right) ; \mathrm{\Delta H}=-\mathrm{x} \mathrm{kJ}$

The value of $\mathrm{x}$ will be:

Consider the following reactions occurring in an automobile, ${\mathrm{C}}_8{\mathrm{H}}_{18}\left(\mathrm{g}\right)+\frac{25}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\to 8{\mathrm{CO}}_2\left(\mathrm{g}\right)+9{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

The sign of $\mathrm{\Delta H}, \mathrm{\Delta S}$ and $\mathrm{\Delta G}$ respectively would be,

Given that

$\mathrm{C}+{\mathrm{O}}_2\to {\mathrm{CO}}_2; ∆\mathrm{H}=-\mathrm{x} \mathrm{kJ}$

$2\mathrm{CO}+{\mathrm{O}}_2\to 2{\mathrm{CO}}_2; \mathrm{\Delta H}=-\mathrm{y} \mathrm{kJ}$

The enthalpy of formation of $\mathrm{CO}$ will be