One mole of an ideal gas is allowed to expand freely and adiabatically into vacuum until its volume has doubled. Which of the following statements is $NOT$ true concerning this expansion?

State $1 \longleftarrow$ State $2 \longleftarrow$ State $3$
$\left(\begin{array}{c} T=300 \ K \\ P=15 \ bar \\ 1 \ mole \end{array}\right) \left(\begin{array}{c} T=300 \ K \\ P=10 \ bar \\ 1 \ mole \end{array}\right) \left(\begin{array}{c} T=300 \ K \\ P=5 \ bar \\ 1 \ mole \end{array}\right)$
The above shows a cyclic process. Calculate the total work done during one complete cycle. (Assume a single step to reach the next state).

$28.0 \, L$ of $CO_2$ is produced on complete combustion of $16.8 \, L$ gaseous mixture of ethene $(C_2H_4)$ and methane $(CH_4)$ at $25^{\circ}C$ and $1 \, atm$. Heat evolved during the combustion process is $......... \, kJ$.
Given :
$\Delta H_C(CH_4) = -900 \, kJ \, mol^{-1}$
$\Delta H_C(C_2H_4) = -1400 \, kJ \, mol^{-1}$

The enthalpy of dilution of $4 \ M \ HCl$ to $2 \ M \ HCl$ is $-2.5 \ kJ/mol$. Find the enthalpy change when $500 \ mL$ of $4 \ M \ HCl$ is diluted to $2 \ M \ HCl$ (in $kJ$).

Calculate $\Delta S_{total}$ for the following reaction at $300 \ K$.
$NH_4NO_{3(s)} \longrightarrow NH_4^+{(aq)} + NO_3^-{(aq)}$ $(\Delta H = 28.1 \ kJ \ mol^{-1}, \Delta S_{sys} = 108.7 \ J \ K^{-1} \ mol^{-1})$

$1 \, mol$ 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 $cal$)