Molar enthalpy change for vapourisation of $1.0 \ mol$ of water at $1.0 \ bar$ and $100 ^{\circ} C$ is $41.0 \ kJ \ mol^{-1}$. If water vapour is assumed to be an ideal gas,the internal energy change for $1.0 \ g$ of water in $kJ$ is

Calculate $\Delta H$ when $2 \ moles$ of solid benzoic acid undergo complete combustion at $300 \ K$ if $C_6H_5COOH_{(s)} + \frac{15}{2} O_{2(g)} \rightarrow 7CO_{2(g)} + 3H_2O_{(l)}$,$\Delta U_{reaction} = -750 \ kJ/mole$ [$R = 8 \ J/mole \cdot K$].

Benzene burns according to the following equation at $300 \ K$ $(R = 8.314 \ J \ mol^{-1} K^{-1})$: $2 C_6H_{6(l)} + 15 O_{2(g)} \to 12 CO_{2(g)} + 6 H_2O_{(l)}$,$\Delta H^o = -6542 \ kJ/mol$. What is the $\Delta E^o$ for the combustion of $1.5 \ mol$ of benzene in $kJ$?

The enthalpy change on freezing of $1 \ mol$ of water at $5 \ ^\circ C$ to ice at $-5 \ ^\circ C$ is ..... $kJ \ mol^{-1}$.
(Given $\Delta _{fus}H = 6 \ kJ \ mol^{-1}$ at $0 \ ^\circ C$,
$C_p(H_2O, l) = 75.3 \ J \ mol^{-1} \ K^{-1}$,
$C_p(H_2O, s) = 36.8 \ J \ mol^{-1} \ K^{-1}$)

The work done during the combustion of $9 \times 10^{-2} \ kg$ of ethane,$C_2H_{6(g)}$ at $300 \ K$ is (Given $R = 8.314 \ J \ K^{-1} \ mol^{-1}$,atomic mass $C = 12$,$H = 1$). (in $kJ$)

The heats of combustion $\Delta H$ of $CH_4$,$C_2H_6$,$C_2H_4$,and $C_2H_2$ gases are $-212.8$,$-373.0$,$-337.0$,and $-310.5 \ kcal$ respectively at the same temperature. Which of these gases is the best fuel?