Compound A used as a strong oxidizing agent is amphoteric in nature. It is the part of lead storage batteries. Compound A is :

The electrode potential of M²⁺/M of 3d-series elements shows positive value for :

For the given cell :

Cu(s) | Cu²⁺(C₁M) || Cu²⁺(C₂M) | Cu(s)

change in Gibbs energy ($$\Delta $$G) is negative, if :

The variation of molar conductivity with concentration of an electrolyte (X) in aqueous solution is shown in the given figure.
The electrolyte X is :