For the spontaneity of a cell,which of the following is correct?

Electrode potential of the half cell $Hg(\ell) | Hg_2Cl_{2(s)} | Cl^-_{(aq)}$ can be increased by

Given at $298 \ K$: $E^\ominus_{Fe^{2+}/Fe} = X \ V$; $E^\ominus_{Fe^{3+}/Fe} = Y \ V$. The $E^\ominus_{Fe^{3+}/Fe^{2+}}$ in Volt at $298 \ K$ is given by:

For the reaction $M^{+n}_{(aq)} + ne^{-} \rightarrow M_{(s)}$,if the standard reduction potentials of elements $M_1, M_2$,and $M_3$ are $-0.34 \ V$,$-3.05 \ V$,and $-1.66 \ V$ respectively,what is the order of their reducing strength?

If in a galvanic cell,the hydrogen half-cell is the anode on the left side,what is the sign of the standard potential of such a galvanic cell? Give an example.

Iron displaces copper from its salt solution,because