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

When $4 \ g$ of iron is burnt to ferric oxide at constant pressure,$29.28 \ kJ$ of heat is evolved. What is the enthalpy of formation of ferric oxide in $kJ \ mol^{-1}$? (At. Wt. of $Fe = 56$)

Given the following thermochemical equations:
$(i) \ H_{2(g)} + \frac{1}{2}O_{2(g)} \rightarrow H_2O_{(l)} ; \Delta H = -68.39 \, kcal$
$(ii) \ K_{(s)} + H_2O_{(l)} + aq \rightarrow KOH_{(aq)} + \frac{1}{2}H_{2(g)} ; \Delta H = -48.0 \, kcal$
$(iii) \ KOH_{(s)} + aq \rightarrow KOH_{(aq)} ; \Delta H = -14.0 \, kcal$
Calculate the heat of formation of $KOH_{(s)}$.

The heat of combustion of solid benzoic acid at constant volume is $-321.30 \ kJ$ at $27^{\circ} C$. The heat of combustion at constant pressure is $(-321.30 - x R) \ kJ$. The value of $x$ is . . . . . . .

The following two reactions are known:
$Fe_2O_{3(s)} + 3CO_{(g)} \rightarrow 2Fe_{(s)} + 3CO_{2(g)}; \Delta H = -26.8 \ kJ$
$FeO_{(s)} + CO_{(g)} \rightarrow Fe_{(s)} + CO_{2(g)}; \Delta H = -16.5 \ kJ$
The value of $\Delta H$ for the following reaction:
$Fe_2O_{3(s)} + CO_{(g)} \rightarrow 2FeO_{(s)} + CO_{2(g)}$ is ............. $kJ$.

Fill in the blanks:
$(i)$ The enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states is called the ....... of that compound.
$(ii)$ The total heat change in a chemical reaction is equal to the algebraic sum of the heat changes of the individual steps of the reaction. This law was given by .......... .
$(iii)$ $A$ process during which there is no exchange of heat between the system and the surroundings is called an ........... process.