The heat of formation of water is $260 \ kJ$. How much $H_2O$ is decomposed by $130 \ kJ$ of heat (in $mol$)?

State and prove Hess's law of constant heat summation.

What is meant by the term average bond enthalpy? Why is there a difference in the bond enthalpy of the $O-H$ bond in ethanol $(C_{2}H_{5}OH)$ and water $(H_{2}O)$?

Calculate the enthalpy change for the following reaction:
$H_2C=CH_{2(g)} + H_{2(g)} \longrightarrow H_3C-CH_{3(g)}$
[The bond energies of $C-H, C-C, C=C$ and $H-H$ are $414, 347, 615$ and $435 \ kJ/mol$ respectively.] (in $kJ$)

If the heat of formation of $CO_2$ is $-393 \ kJ/mol$,the amount of heat evolved in the formation of $0.156 \ kg$ of $CO_2$ is.....$kJ$.

For the reaction $Cu_{(g)}^{+} + I_{(g)}^{-} \to CuI_{(s)}$,the value of $\Delta H^o$ is $-446 \ kJ \ mol^{-1}$. If the ionization energy of $Cu_{(g)}$ is $745 \ kJ \ mol^{-1}$ and the electron affinity of $I_{(g)}$ is $-295 \ kJ \ mol^{-1}$,calculate the value of $\Delta H^o$ for the formation of $CuI_{(s)}$ from $Cu_{(g)}$ and $I_{(g)}$ in $kJ \ mol^{-1}$.