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 ?

If the emf of cell, $\text{Cu}_{(s)} \mid \text{Cu}^{2+}_{(1M)} \| \text{Ag}^{+}_{(1M)} \mid \text{Ag}$ is 0.463 V at $25\ ^\circ\text{C}$ and standard potential of Cu electrode is 0.337 V. Find the standard potential of Ag electrode

Which of the following hot aqueous solutions is used to dip carbon rods of $\text{H}_2 - \text{O}_2$ fuel cell ?