Identify the correct statement from following.

What is the change in oxidation number of Pb at positive electrode of lead accumulator acting as galvanic cell ?

The graphical variation of molar conductivity $(\Lambda)$ against square root of molar concentration $(\sqrt{c})$ of certain electrolyte 'X' is linear with intercept on y axis. Identify X from following.

If standard reduction potential $(E^0)$ of $\left(\text{Al}^{+3}_{(aq)}|\text{Al}_{(s)}\right)$, $\left(\text{Fe}^{+2}_{(aq)}|\text{Fe}_{(s)}\right)$, $\left(\text{Cu}^{+2}_{(aq)}|\text{Cu}_{(s)}\right)$ and $\left(\text{Ag}^{+1}_{(aq)}|\text{Ag}_{(s)}\right)$ are $-1 \cdot 66$ V, $-0 \cdot 44$ V, $+0 \cdot 34$ V and $+0 \cdot 79$ V respectively. Which of the following reaction is non spontaneous ?