The $E^{\circ}$ of $\mathrm{Ce}^{4+} / \mathrm{Ce}^{3+}=1.6 \mathrm{~V}, \mathrm{Fe}^{3+} / \mathrm{Fe}^{2+}=0.76 \mathrm{~V}$ the $E^{\circ}$ of $\mathrm{Fe}^{3+}$ oxidising $\mathrm{Ce}^{3+}$ is

Electrolysis of aqueous $\mathrm{Na}_2 \mathrm{SO}_4$ was carried out by passing a current of 3 ampere for 10 min . The volume of the gas (in litre) at STP at the anode of the cell is approximately

The variation of $\lambda_{\mathrm{m}}$ of acetic acid with concentration is correctly represented as