The bond dissociation energies of $X_2$,$Y_2$ and $XY$ are in the ratio of $1 : 0.5 : 1$. $\Delta H$ for the formation of $XY$ is $-200 \ kJ \ mol^{-1}$. The bond dissociation energy of $X_2$ will be $...... \ kJ \ mol^{-1}$.

The enthalpy change for the conversion of $\frac{1}{2} Cl_{2(g)}$ to $Cl^{-}_{(aq)}$ is $......$ $kJ \, mol^{-1}$ (Nearest integer).
Given:
$\Delta_{dis}H^{\circ}_{Cl_{2(g)}} = 240 \, kJ \, mol^{-1}$
$\Delta_{eg}H^{\circ}_{Cl_{(g)}} = -350 \, kJ \, mol^{-1}$
$\Delta_{hyd}H^{\circ}_{Cl^{-(g)}} = -380 \, kJ \, mol^{-1}$

The heat of combustion of ethanol in a bomb calorimeter at $25^{\circ}C$ is $-670.48 \, kcal \, mol^{-1}$. What is the value of $\Delta H$ for this reaction at $25^{\circ}C$ in $kcal$?

In the following reaction,how much enthalpy change in $kJ$ is associated with the formation of $5.67 \ mol$ of $HCl$ gas? $H_{2(g)} + Cl_{2(g)} \to 2HCl_{(g)} \; ; \Delta H = -184.6 \ kJ$

The heat of formation of $H_2O_{(l)}$ is $-68.0 \ kcal$. The heat of formation of $H_2O_{(g)}$ is likely to be........$kcal$.

Energy required to dissociate $16 \ g$ of $O_{2(g)}$ into free atoms is $x \ kJ$. The value of bond enthalpy of $O=O$ bond is