Consider the following :

Statement I : During isothermal expansion of an ideal gas its enthalpy decreases.

Statement II : When 2.0 L of an ideal gas expands isothermally into vaccum, $\Delta U=0$.

The correct answer is :

The energy required to increase the temperature of 180 g of liquid water from $10^{\circ} \mathrm{C}$ to $15^{\circ} \mathrm{C}$ is 3765 J . What is $C_p$ of water in $\mathrm{J} \mathrm{mol}^{-1} \mathrm{~K}^{-1} ?\left(\mathrm{H}_2 \mathrm{O}=18 \mathrm{u}\right)$

At $25^{\circ} \mathrm{C}$, the percentage of ionisation of $x \mathrm{M}$ acetic acid is 4.242 . What is the pH of the acetic acid solution?

$$ \begin{aligned} & (\log 4.242=0.6275) ;(\log 0.04242=-1.372) \\ & \left(K_{\mathrm{a}}=1.8 \times 10^{-5}\right) \end{aligned} $$

At 298 K , the value of $K_c$ for the following reaction is $x \mathrm{~mol} \mathrm{~L}^{-1}$.

What is the approximate $K_{\mathrm{P}}$ value for this reaction?

$$ \begin{array}{r} \left(R=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}\right) \\ \mathrm{A}_2 \mathrm{O}_4(\mathrm{~g}) \rightleftharpoons 2 \mathrm{AO}_2(\mathrm{~g}) \end{array} $$