The heat of formation of $SiO_2$ and $MgO$ is respectively $-48.4 \ kJ$ and $-34.7 \ kJ$. The heat of the reaction $2Mg + SiO_2 \to 2MgO + Si$ is $...... \ kJ$.

The standard enthalpy of formation of $NH_3$ is $-46.0 \, kJ/mol$. If the enthalpy of formation of $H_2$ from its atoms is $-436 \, kJ/mol$ and that of $N_2$ is $-712 \, kJ/mol$,the average bond enthalpy of $N-H$ bond in $NH_3$ is......$kJ/mol$

Consider the following reaction:
$C_{(s)} + O_{2(g)} \to CO_{2(g)} + x \ kJ$
$CO_{(g)} + \frac{1}{2}O_{2(g)} \to CO_{2(g)} + y \ kJ$
The heat of formation of $CO_{(g)}$ is:

The heat of neutralisation of one equivalent of an acid by one equivalent of a base is minimum when:

Given that $C_{(g)} + 4H_{(g)} \longrightarrow CH_{4(g)}$,$\Delta H^{\circ} = -1665 \ kJ$. What is the bond energy per mole of $C-H$ bond?

The heat of combustion of carbon is $-393.5 \ kJ / mol$. The heat released upon the formation of $35.2 \ g$ of $CO_{2}$ from carbon and oxygen gas is