On combustion,carbon forms two oxides $CO$ and $CO_2$. The heat of formation of $CO_2$ gas is $-94.3 \, kcal$ and that of $CO$ is $-26.0 \, kcal$. The heat of combustion of carbon is.......$kcal$.

Average $C-H$ bond energy is $416 \ kJ \ mol^{-1}$. Which of the following is correct?

"The resultant heat change in a reaction is the same whether it takes place in one or several stages." This statement is called

The standard enthalpy of formation of $CO_{2(g)}$,$CaO_{(s)}$ and $CaCO_{3(s)}$ are $-393, -634, -1210 \ kJ \ mol^{-1}$ respectively. If all the substances are in standard state,the standard enthalpy of decomposition of calcium carbonate to $CaO_{(s)}$ and $CO_{2(g)}$ (in $kJ \ mol^{-1}$) is

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

Given that,$C_{(s)} + O_{2(g)} \longrightarrow CO_{2(g)} ; \Delta H^{\circ} = -x \ kJ \ mol^{-1}$ and $2CO_{(g)} + O_{2(g)} \longrightarrow 2CO_{2(g)} ; \Delta H^{\circ} = -y \ kJ \ mol^{-1}$. The enthalpy of formation of $CO$ will be: