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.......$kcal$.

Calculate the enthalpy change of the reaction for $H_2(g) + Cl_2(g) \rightarrow 2HCl(g)$, given the bond energies (in $\text{kJ mol}^{-1}$): $H-H = 436$, $Cl-Cl = 242$, $H-Cl = 431$.

The bond dissociation enthalpy of $H_{2(g)}$ and $N_{2(g)}$ are $436 \ kJ \ mol^{-1}$ and $940 \ kJ \ mol^{-1}$ respectively,and the enthalpy of formation of $NH_{3(g)}$ is $-45 \ kJ \ mol^{-1}$. The enthalpy of atomisation of $NH_{3(g)}$ is ..... $kJ \ mol^{-1}$.

The standard heats of formation in $kcal \ mol^{-1}$ of $NO_{2(g)}$ and $N_2O_{4(g)}$ are $8.0$ and $2.0$ respectively. The heat of dimerization of $NO_2$ in $kcal$ for the reaction $2NO_{2(g)} \rightarrow N_2O_{4(g)}$ is:

What is the enthalpy change for the reaction $NaOH_{(aq)} + HCl_{(aq)} \rightarrow NaCl_{(aq)} + H_2O_{(l)}$ called?

Write notes on diatomic molecules and polyatomic molecules with respect to bond dissociation enthalpy.