Which of the following values of heat of formation indicates that the product is least stable in $kcal$?

For strong acid and strong base neutralisation,the net chemical change is $H^{+} + OH^{-} \longrightarrow H_2O_{(l)}$; $\Delta_r H^{\circ} = -55.84 \ kJ \ mol^{-1}$. If the enthalpy of neutralisation of $CH_3COOH$ by $NaOH$ is $-49.86 \ kJ \ mol^{-1}$,then the enthalpy of ionisation of $CH_3COOH$ is:

Given:
$I$. $2Fe_{(s)} + \frac{3}{2} O_{2(g)} \to Fe_2O_{3(s)}$; $\Delta H^{\Theta} = -193.4 \ kJ$
$II$. $Mg_{(s)} + \frac{1}{2} O_{2(g)} \to MgO_{(s)}$; $\Delta H^{\Theta} = -140.2 \ kJ$
What is $\Delta H^{\Theta}$ of the reaction?
$3Mg_{(s)} + Fe_2O_{3(s)} \to 3MgO_{(s)} + 2Fe_{(s)}$
....... $kJ$

Calculate the heat of reaction for the process: $NH_3(g) + HCl(g) \rightarrow NH_4Cl(s)$ given the following data:
$(i)$ $NH_3(g) + aq \rightarrow NH_3(aq)$,$\Delta H = -8.4 \, Kcal$
$(ii)$ $HCl(g) + aq \rightarrow HCl(aq)$,$\Delta H = -17.3 \, Kcal$
$(iii)$ $NH_3(aq) + HCl(aq) \rightarrow NH_4Cl(aq)$,$\Delta H = -12.5 \, Kcal$
$(iv)$ $NH_4Cl(s) + aq \rightarrow NH_4Cl(aq)$,$\Delta H = +3.9 \, Kcal$ (in $, Kcal$)

The standard enthalpy of formation,$\Delta H^o_f$ $(298 \ K)$,of methanol is represented by which of the following chemical equations?

When $0.5 \ mol$ of $HNO_3$ reacts with $0.2 \ mol$ of $KOH$,the heat of neutralization is equal to ...... $kJ$.