$A$ gas at $10 \, atm$ pressure and $300 \, K$ temperature undergoes adiabatic reversible expansion to $5 \, atm$ pressure and $290 \, K$ temperature. The molar heat capacity $C_v$ of the gas in $cal \, mol^{-1} \, K^{-1}$ is:

$A$ liquid confined inside an adiabatic container is taken from state $1$ to state $2$ by a single-stage process as shown in the $P-V$ diagram. Then,$\Delta H$ is:

Match the transformations in column $I$ with appropriate options in column $II$.

Column $I$	Column $II$
$A$. $CO_{2(s)} \rightarrow CO_{2(g)}$	$p$. phase transition
$B$. $CaCO_{3(s)} \rightarrow CaO_{(s)} + CO_{2(g)}$	$q$. allotropic change
$C$. $2H_{(g)} \rightarrow H_{2(g)}$	$r$. $\Delta H$ is positive
$D$. $P_{(\text{white, solid})} \rightarrow P_{(\text{red, solid})}$	$s$. $\Delta S$ is positive
	$t$. $\Delta S$ is negative

Calculate the work done for the following reaction at $27^{\circ}C$: $C_2H_4(g) + H_2(g) \rightarrow C_2H_6(g)$ $(R = 8.314 \text{ J K}^{-1} \text{mol}^{-1})$ (in $\text{ J}$)

Which of the following is incorrect?

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 $55.85 \ u$]