"The quantity of heat which must be supplied to decompose a compound into its elements is equal to the heat evolved during the formation of that compound from the elements." This statement is known as

One mole of acetone requires less heat to vaporise than $1$ mol of water. Which of the two liquids has higher enthalpy of vaporisation?

For the reaction,$2 H_{2(g)} + O_{2(g)} \longrightarrow 2 H_{2}O_{(g)}$,$\Delta H^{\circ} = -573.2 \ kJ$. The heat of decomposition of water per mole is

Given the following data:

Reaction	Energy Change (in $kJ$)
$Li_{(s)} \to Li_{(g)}$	$161$
$Li_{(g)} \to Li^{+}_{(g)}$	$520$
$\frac{1}{2} F_{2(g)} \to F_{(g)}$	$77$
$F_{(g)} + e^- \to F^{-}_{(g)}$	(Electron gain enthalpy)
$Li^{+}_{(g)} + F^{-}_{(g)} \to LiF_{(s)}$	$-1047$
$Li_{(s)} + \frac{1}{2} F_{2(g)} \to LiF_{(s)}$	$-617$

Based on the data provided,the value of electron gain enthalpy of fluorine would be $kJ\ mol^{-1}$.

What will be the standard heat of reaction for the reaction $C_2H_{6(g)} + 7/2 O_{2(g)} \to 2CO_{2(g)} + 3H_2O_{(l)}$ if the standard heat of combustion of $C_{(s)}$ and $H_{2(g)}$ are $-393.5 \ kJ/mol$ and $-285 \ kJ/mol$ respectively,and the standard heat of formation of $C_2H_{6(g)}$ is $-88.2 \ kJ/mol$?

The bond dissociation energies of gaseous $H_2$,$Cl_2$ and $HCl$ are $104$,$58$ and $103 \ kcal$ respectively. The enthalpy of formation of $HCl$ gas would be $... \ kcal$.