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

Given that the heat of reaction for $A + \frac{1}{2} O_2 \to AO$ is $-50 \ kcal$ and for $AO + \frac{1}{2} O_2 \to AO_2$ is $100 \ kcal$. Find the heat of reaction for $A + O_2 \to AO_2$ in $kcal$.

Which of the following is an endothermic reaction?

If the enthalpies of atomization of methane and ethane are respectively $320 \ cal$ and $360 \ cal$,then the bond energy of the $C-C$ bond is......$cal$.

The heat of complete neutralization of $1 \ mol$ of $H_2SO_4$ with a strong base is ....... $Kcal$.

According to the following figure,the magnitude of the enthalpy change of the reaction $A+B \rightarrow M+N$ in $kJ \ mol^{-1}$ is equal to ...... .