If heat of neutralization is $-13.7 \, KCal$ at $25 \, ^oC$ and $\Delta H_f^o (H_2O) = -68 \, KCal$,then the standard enthalpy of formation of $OH^{-}$ will be.....$KCal$. (in $.3$)

Consider the reaction $4NO_2(g) + O_2(g) \rightarrow 2N_2O_5(g)$, $\Delta_rH = -111 \ kJ$. If $N_2O_5(s)$ is formed instead of $N_2O_5(g)$, what will be the value of $\Delta_rH$ in $kJ$? (Given: $\Delta H_{sub} = 54 \ kJ \ mol^{-1}$ for $N_2O_5$)

Calculate the standard enthalpy of combustion of carbon monoxide $(CO)$ given that $\Delta_f H^{\circ}(CO) = -110 \text{ kJ mol}^{-1}$ and $\Delta_f H^{\circ}(CO_2) = -393 \text{ kJ mol}^{-1}$.

Calculate the heat of formation of $HCl$ gas from the following reaction: $H_{2(g)} + Cl_{2(g)} \rightarrow 2 HCl_{(g)} ; \Delta H = -194 \ kJ$

Given the following thermochemical equations:
$(1) \ H_2O_{(g)} + C_{(s)} \to CO_{(g)} + H_{2(g)} ; \Delta H_1 = 100 \ kJ$
$(2) \ CO_{(g)} + \frac{1}{2}O_{2_{(g)}} \to CO_{2_{(g)}} ; \Delta H_2 = -300 \ kJ$
$(3) \ H_{2(g)} + \frac{1}{2}O_{2_{(g)}} \to H_2O_{(g)} ; \Delta H_3 = -250 \ kJ$
Calculate the value of $x$ for the reaction:
$(4) \ C_{(s)} + O_{2_{(g)}} \to CO_{2_{(g)}} ; \Delta H_4 = -x \ kJ$

The heat of neutralization of a weak acid and a strong base is less than the heat of neutralization of a strong acid and a strong base due to: