Bond dissociation enthalpy of $H_2, Cl_2$ and $HCl$ are $434, 242$ and $431 \ kJ \ mol^{-1}$ respectively. Enthalpy of formation of $HCl$ is ............... $kJ \ mol^{-1}$

The heat of neutralization of $HCl$ and $NaOH$ is:

Given:
$(I) \ H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(l)}; \Delta H^o_{298\ K} = -285.9 \ kJ \ mol^{-1}$
$(II) \ H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(g)}; \Delta H^o_{298\ K} = -241.8 \ kJ \ mol^{-1}$
The molar enthalpy of vaporisation of water will be $kJ \ mol^{-1}$.

The enthalpies of formation of $N_2O$ and $NO$ are $28$ and $90 \ kJ \ mol^{-1}$ respectively. The enthalpy of the reaction,$2N_2O_{(g)} + O_{2(g)} \to 4NO_{(g)}$ is equal to.....$kJ$

$H_{2(g)} + \frac{1}{2} O_{2(g)} \to H_2O_{(g)}$
$B.E. (H-H) = x_1$; $B.E. (O=O) = x_2$;
$B.E. (O-H) = x_3$
Heat of vaporisation of water $= x_4$,then $\Delta H_f$ [heat of formation of liquid water] is:

What do you understand by exothermic reaction and endothermic reaction? Give one example of each type.