At $25$ $^\circ C$ and $1$ $atm$ pressure,the enthalpies of formation of $C_2H_4(g)$,$CO_2(g)$,and $H_2O(l)$ are $52$,$-394$,and $-286 \, kJ \, mol^{-1}$ respectively. The enthalpy of combustion of $C_2H_4$ is ....... $kJ \, mol^{-1}$.

For isothermal expansion of an ideal gas,the correct combination of the thermodynamic parameters will be

$1 \, mol$ of oxygen gas is heated at constant volume from $20 \, ^oC$ to $30 \, ^oC$. What will be the change in the internal energy of the gas? Given the molar heat capacity of oxygen at constant pressure,$C_P = 7.03 \, cal \, mol^{-1} \, K^{-1}$ and $R = 2 \, cal \, mol^{-1} \, K^{-1}$. (Answer in $cal$)

Find the heat required to convert $10 \ g$ of ice at $0.0^{\circ} C$ into water at $30^{\circ} C$. (Enthalpy of fusion of ice $= 333.5 \ J \ g^{-1}$,$C_p$ of water $= 4.18 \ J \ g^{-1} \ K^{-1}$) (in $kJ$)

The enthalpy of sublimation of $I_{2(s)}$ is $57.3 \, kJ \, mol^{-1}$ and the enthalpy of fusion is $15.5 \, kJ \, mol^{-1}$. The enthalpy of vaporization of $I_2$ is ..................... $kJ \, mol^{-1}$. (in $.8$)

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?