The heat of combustion of ethanol into carbon dioxide and water is $-327 \ kcal$ at constant pressure. The heat evolved (in $cal$) at constant volume and $27^{\circ} C$ (assuming all gases behave ideally) is $\left( R = 2 \ cal \ mol^{-1} \ K^{-1} \right)$

$C_{(s)} + O_{2(g)} \rightarrow CO_{2(g)} \dots \dots(I) \quad \Delta H = -393 \, kJ \, mol^{-1}$
$H_{2(g)} + \frac{1}{2} O_{2(g)} \rightarrow H_{2}O_{(l)} \dots \dots(II) \quad \Delta H = -287.3 \, kJ \, mol^{-1}$
$2CO_{2(g)} + 3H_{2}O_{(l)}$ $\rightarrow C_{2}H_{5}OH_{(l)} + 3O_{2(g)} \dots \dots(III) \quad \Delta H = 1366.8 \, kJ \, mol^{-1}$
Find the standard enthalpy of formation of $C_{2}H_{5}OH_{(l)}$.

Energy required to dissociate $4 \ g$ of gaseous hydrogen into free gaseous atoms is $208 \ kcal$ at $25 \ ^oC$. The bond energy of $H-H$ bond will be

The bond dissociation enthalpy of $H_{2(g)}$ and $N_{2(g)}$ are $436 \ kJ \ mol^{-1}$ and $940 \ kJ \ mol^{-1}$ respectively,and the enthalpy of formation of $NH_{3(g)}$ is $-45 \ kJ \ mol^{-1}$. The enthalpy of atomisation of $NH_{3(g)}$ is ..... $kJ \ mol^{-1}$.

For the reaction $\frac{1}{2} X_2O_{(s)} \to X_{(s)} + \frac{1}{4} O_{2(g)}$ with $\Delta H = 90 \ kJ$,the enthalpy change for the reaction of $1 \ mol$ of $O_2$ with metal $X$ is ................ $kJ$.

When $50 \ cm^3$ of a strong acid is added to $50 \ cm^3$ of an alkali,the temperature rises by $5 \ ^oC$. If $250 \ cm^3$ of each liquid are mixed,the temperature rise would be $... \ ^oC$.