Copper is to be electrodeposited on a nickel block of $(20 \times 5) \mathrm{cm}^2$ area by using $\mathrm{CuSO}_4$ as electrolyte. How much quantity of electricity is needed to deposit a 3.6 $\mu \mathrm{m}$ layer of copper?

[Atomic weight of $\mathrm{Cu}=63.5 \mathrm{~mol}^{-1}$ Density of $\mathrm{CuSO}_4=8.9 \mathrm{~g} / \mathrm{cc}$ ]

A solution of $\mathrm{Fe}^{2+}$ is titrated potentiometrically using $\mathrm{Ce}^{4+}$ solution. When $80 \% \mathrm{Fe}^{2+}$ is titrated, the EMF of the system in $V$ is

(Given, $E^{\circ} \mathrm{Fe}^{3+} / \mathrm{Fe}^{2+}=0.77 \mathrm{~V}$ and $\left.\mathrm{Fe}^{2+}+\mathrm{Ce}^{4+} \longrightarrow \mathrm{Fe}^{3+}+\mathrm{Ce}^{3+}\right) (\log 2=0.3, \log 3=0.5, \log 4=0.6)$

What is the standard cell potential for the reaction with $K=1$ (equilibrium constant)

The maximum work that can be obtained from the following cells is

$$ X\left|X^{2+}(a q) \| Y^{+}(a q)\right| Y $$

Given, $E_{X^{2+} / X}^{\circ}=-1.7 \mathrm{~V}, E_{Y^{2+} / Y}^{\circ}=0.8 \mathrm{~V}$