For the reaction $X_2O_{4(g)} \to 2XO_{2(g)}$,given $\Delta U = 2.1 \, kcal$ and $\Delta S = 20 \, cal \, K^{-1}$ at $300 \, K$. Calculate $\Delta G$ in $kcal$.

At $25^{\circ} C$,$50 \ g$ of iron reacts with $HCl$ to form $FeCl_2$. The evolved hydrogen gas expands against a constant pressure of $1 \ bar$. The work done by the gas during this expansion is ....... $J$. (Round off to the Nearest Integer) [Given : $R = 8.314 \ J \ mol^{-1} \ K^{-1}$. Assume,hydrogen is an ideal gas] [Atomic mass of $Fe$ is $55.85 \ u$]

Match the following items in List-$I$ with their corresponding expressions in List-$II$.

List-$I$	List-$II$
$A$. At constant volume the change in internal energy of a system	$I$. $W = -2.303 nRT \log \frac{V_f}{V_i}$
$B$. Isothermal irreversible change	$II$. $W_{adiabatic} = \Delta U$
$C$. Isothermal reversible change	$III$. $q_V = \Delta U$
$D$. Adiabatic change	$IV$. $W = -p_{ex} (V_f - V_i)$
	$V$. $\Delta U = \Delta H - \Delta nRT$

In an irreversible process taking place at constant $T$ and $P$ and in which only pressure-volume work is being done,the change in Gibbs free energy $(dG)$ and change in entropy $(dS)$ satisfy the criteria:

What is the difference between $\Delta H$ and $\Delta U$ for the combustion of methane at $25\,^oC$?

Consider the following data for the reaction $X_2(g) + Y_2(g) \rightleftharpoons 2XY(g)$ at $600 \ K$. The $\Delta_r G^\circ$ (in $kJ \ mol^{-1}$) for the reaction is:

Compound	$\Delta_f H^\circ$ $(kJ \ mol^{-1})$	$S^\circ$ $(J \ mol^{-1} \ K^{-1})$
$XY(g)$	$42$	$200$
$X_2(g)$	$8$	$140$
$Y_2(g)$	$80$	$250$