The average $S-F$ bond energy in $kJ \ mol^{-1}$ of $SF_{6}$ is $......$ . (Rounded off to the nearest integer) [Given : The values of standard enthalpy of formation of $SF_{6(g)}$,$S_{(g)}$ and $F_{(g)}$ are $-1100$,$275$ and $80 \ kJ \ mol^{-1}$ respectively.]

At $298 \ K$,the enthalpy of fusion of a solid $(X)$ is $2.8 \ kJ \ mol^{-1}$ and the enthalpy of vaporisation of the liquid $(X)$ is $98.2 \ kJ \ mol^{-1}$. The enthalpy of sublimation of the substance $(X)$ in $kJ \ mol^{-1}$ is $.....$ (in nearest integer).

The standard enthalpy of formation,$\Delta H^o_f$ $(298 \ K)$,of methanol is represented by which of the following chemical equations?

Identify the $INVALID$ equation.

At $25^{\circ} \text{C}$, the standard enthalpies of combustion of $H_2(g)$, cyclohexene $(C_6H_{10})$, and cyclohexane $(C_6H_{12})$ are $-241 \text{ kJ mol}^{-1}$, $-3800 \text{ kJ mol}^{-1}$, and $-3920 \text{ kJ mol}^{-1}$ respectively. Calculate the heat of hydrogenation of cyclohexene.

The enthalpy changes at $298 \ K$ in successive breaking of $O-H$ bonds of $H_2O$ are:
$H_2O_{(g)} \to H_{(g)} + OH_{(g)}, \Delta H = 498 \ kJ \ mol^{-1}$
$OH_{(g)} \to H_{(g)} + O_{(g)}, \Delta H = 428 \ kJ \ mol^{-1}$
The bond enthalpy of the $O-H$ bond is ..... $kJ \ mol^{-1}$.