An electrochemical cell differs from the electrolytic cell in many respects, one of the statements regarding this is wrong.

Which of the following will increase the voltage of the cell?

${\mathrm{Sn}}_{\left(\mathrm{s}\right)}+2{\mathrm{Ag}}_{\left(\mathrm{aq}\right)}^{+}⟶{\mathrm{Sn}}_{\left(\mathrm{aq}\right)}^{2+}+2{\mathrm{Ag}}_{\left(\mathrm{s}\right)}$

Which is the strongest reducing agent?

Standard reduction potential of ${\mathrm{Zn}}^{2+}\left(\mathrm{aq}\right)/\mathrm{Zn}; {\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right)/\mathrm{Cu}$
and ${\mathrm{Fe}}^{2+}\left(\mathrm{aq}\right)/\mathrm{Fe}$ being $-0.762,+0.340$ and $-0.440$ volt respectively.

Given${\mathrm{E}}_{{\mathrm{Zn}}^{2+}/\mathrm{Zn}}^{\mathrm{\Theta }}=-0.76 \mathrm{V},{\mathrm{E}}_{{\mathrm{Ni}}^{2+}/\mathrm{Ni}}^{\mathrm{\Theta }}=-0.25 \mathrm{V}.$ Calculate the e.m.f. of the cell where the following reactions is taking place.

$\mathrm{Zn}\left(\mathrm{s}\right)+{\mathrm{Ni}}^{2+}\left(\mathrm{aq}\right)⟶{\mathrm{Zn}}^{2+}+\mathrm{Ni}\left(\mathrm{s}\right)$