The values of $\Delta H$ for the combustion of ethene and ethyne are $-341.1 \ kcal$ and $-310.0 \ kcal$ respectively. Which of the following is a better fuel?

$C_{(graphite)} + O_{2(g)} \to CO_{2(g)}; \Delta H = - 94.05 \ k \ cal \ mol^{-1}$
$C_{(diamond)} + O_{2(g)} \to CO_{2(g)}; \Delta H = - 94.50 \ k \ cal \ mol^{-1}$
Therefore:

The standard entropies of $X_2, Y_2$ and $XY_3$ are $60, 40$ and $50 \ J \ K^{-1} \ mol^{-1}$ respectively. For the reaction $X_2 + 3Y_2 \rightleftharpoons 2XY_3; \Delta H = -60 \ kJ$ to be at equilibrium,the temperature should be.....$K$

Assuming the water vapour to be a perfect gas,calculate the internal energy change when $1 \ mol$ of water at $100^{\circ} C$ and $1 \ bar$ pressure is converted to ice at $0^{\circ} C$. Given the enthalpy of fusion of ice is $6.00 \ kJ \ mol^{-1}$ and heat capacity of water is $4.2 \ J \ g^{-1} {\circ} C^{-1}$.

Which of the following is true for the reaction $H_2O_{(l)} \rightleftharpoons H_2O_{(g)}$ at $100 ^oC$ and $1 \text{atm}$ pressure?

For the process $H_2O_{(l)} (1 \, bar, 373 \, K) \rightarrow H_2O_{(g)} (1 \, bar, 373 \, K)$,identify the correct thermodynamic parameters.