The enthalpy change $(\Delta H)$ for the process $N_2H_{4(g)} \to 2N_{(g)} + 4H_{(g)}$ is $1724 \ kJ \ mol^{-1}$. If the bond energy of $N-H$ bond in ammonia is $391 \ kJ \ mol^{-1}$,what is the bond energy of $N-N$ bond in $N_2H_4$ in $kJ \ mol^{-1}$?

Given the following thermochemical equations:
$C_{(s)} + O_{2_{(g)}} \to CO_{2_{(g)}} + 94.2 \, kcal$
$H_{2_{(g)}} + \frac{1}{2} O_{2_{(g)}} \to H_2O_{(l)} + 68.3 \, kcal$
$CH_{4_{(g)}} + 2O_{2_{(g)}} \to CO_{2_{(g)}} + 2H_2O_{(l)} + 210.8 \, kcal$
Calculate the heat of formation of methane in $kcal$.

The bond dissociation enthalpy of $X_2$,$\Delta H_{\text{bond}}^{\circ}$,calculated from the given data is $...$ $kJ \ mol^{-1}$. (Nearest integer)
$M^{+}X^{-}_{(s)} \rightarrow M^{+}_{(g)} + X^{-}_{(g)} \quad \Delta H_{\text{lattice}}^{\circ} = 800 \ kJ \ mol^{-1}$
$M_{(s)} \rightarrow M_{(g)} \quad \Delta H_{\text{sub}}^{\circ} = 100 \ kJ \ mol^{-1}$
$M_{(g)} \rightarrow M^{+}_{(g)} + e^{-}_{(g)} \quad \Delta H_{i}^{\circ} = 500 \ kJ \ mol^{-1}$
$X_{(g)} + e^{-}_{(g)} \rightarrow X^{-}_{(g)} \quad \Delta H_{\text{eg}}^{\circ} = -300 \ kJ \ mol^{-1}$
$M_{(s)} + \frac{1}{2}X_{2(g)} \rightarrow M^{+}X^{-}_{(s)} \quad \Delta H_{f}^{\circ} = -400 \ kJ \ mol^{-1}$
[Given : $M^{+}X^{-}$ is a pure ionic compound and $X$ forms a diatomic molecule $X_2$ in gaseous state]

Hess's law is applicable for the determination of heat of

Which of the following statements is correct?

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