If $C_{(s)} + O_{2(g)} \rightarrow CO_{2(g)}$,$\Delta H = -X$,and $CO_{(g)} + \frac{1}{2} O_{2(g)} \rightarrow CO_{2(g)}$,$\Delta H = -Y$,calculate $\Delta_f H$ for $CO_{(g)}$ formation.

The enthalpy change for the reaction,$C_{2}H_{6(g)} \to 2C_{(g)} + 6H_{(g)}$ is $X \ kJ$. The bond energy of $C-H$ bond is :-

The enthalpy of vaporisation of $CCl_4$ is $30.5 \ kJ \ mol^{-1}$. Calculate the heat required for the vaporisation of $284 \ g$ of $CCl_4$ at constant pressure. (Molar mass of $CCl_4 = 154 \ g \ mol^{-1}$).

$H_2 + \frac{1}{2} O_2 \to H_2O; \Delta H = -68.39 \ kcal$
$K + H_2O + \text{water} \to KOH_{(aq)} + \frac{1}{2} H_2; \Delta H = -48 \ kcal$
$KOH + \text{water} \to KOH_{(aq)}; \Delta H = -14 \ kcal$
The heat of formation of $KOH$ is (in $kcal$):

The combustion enthalpies of carbon,hydrogen,and methane are $-393.5 \ kJ/mole$,$-284.8 \ kJ/mole$,and $-890.4 \ kJ/mole$ respectively at $25 \ ^oC$. The value of the standard formation enthalpy of methane at that temperature is ..... $kJ/mole$.

Which of the following compounds will absorb the maximum quantity of heat when dissolved in the same amount of water? The heats of solution of these compounds at $25 \, ^\circ C$ in $kJ/mole$ of each solute are given in brackets.