The enthalpy of combustion at $25\,^{\circ}C$ of $H_2$,cyclohexene $(C_6H_{10})$ and cyclohexane $(C_6H_{12})$ are $-241$,$-3800$ and $-3920 \ kJ/mol$ respectively. The heat of hydrogenation of cyclohexene is.....$kJ/mol$.

The enthalpies of combustion of diamond and graphite are $-395.4 \, kJ$ and $-393.5 \, kJ$ respectively. The enthalpy of transformation of diamond to graphite is ..... $kJ$.

Calculate the enthalpy of formation of ethylene $(C_2H_4)$ from the following data:
$I. C_{(graphite)} + O_{2(g)} \rightarrow CO_{2(g)}; \Delta H = -393.5 \ kJ$
$II. H_{2(g)} + \frac{1}{2}O_{2(g)} \rightarrow H_2O_{(l)}; \Delta H = -286.2 \ kJ$
$III. C_2H_{4(g)} + 3O_{2(g)} \rightarrow 2CO_{2(g)} + 2H_2O_{(l)}; \Delta H = -1410.8 \ kJ$ (in $kJ$)

The enthalpy of combustion of propane,graphite and dihydrogen at $298 \ K$ are: $-2220.0 \ kJ \ mol^{-1}$,$-393.5 \ kJ \ mol^{-1}$ and $-285.8 \ kJ \ mol^{-1}$ respectively. The magnitude of the enthalpy of formation of propane $(C_{3}H_{8})$ is ......... $kJ \ mol^{-1}$. (Nearest integer)

"The resultant heat change in a reaction is the same whether it takes place in one or several stages." This statement is called

For the reaction $2H_2O_2(\ell) \to 2H_2O(\ell) + O_2(g)$,what is the enthalpy change? Given that the heats of formation of $H_2O_2(\ell)$ and $H_2O(\ell)$ are $-188 \, kJ/mol$ and $-286 \, kJ/mol$ respectively.