Consider galvanic cell, ${ }^{\ominus} \mathrm{A}_{(\mathrm{s})}\left|\mathrm{A}_{(\mathrm{aq})}^{+2}\right|\left|\mathrm{B}_{(\mathrm{aq})}^{+}\right| \mathrm{B}_{(\mathrm{s})}^{\oplus}$

if emf of cell is positive, identify a correct cell reaction from following.

Standard potential of electrode reaction $\mathrm{Cu}_{(\mathrm{aq})}^{+2}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Cu}_{(\mathrm{s})}$ is +0.34 V .

What is standard potential of reaction

$$ 2 \mathrm{Cu}_{(\mathrm{s})} \longrightarrow 2 \mathrm{Cu}_{(\mathrm{aq})}^{+2}+4 \mathrm{e}^{-} ? $$

What is value of $E_{\text {cell }}$ at 298 K for the reaction, $\mathrm{Zn}_{(\mathrm{s})}+\mathrm{Cu}^{+2}(0.1 \mathrm{M}) \longrightarrow \mathrm{Zn}^{+2}(0.1 \mathrm{M})+\mathrm{Cu}_{(\mathrm{s})}$ if $\mathrm{E}_{\text {cell }}^{\circ}=1.1 \mathrm{~V}$ ?

$$ \begin{aligned} & \text { If } \mathrm{E}^{\circ}\left(\mathrm{Fe}_{(\mathrm{aq})}^{+2} \mid \mathrm{Fe}_{(\mathrm{s})}\right)=-0.44 \mathrm{~V} \text { and } \\ & \mathrm{E}^{\circ}\left(\mathrm{Sn}_{(\mathrm{aq})}^{+2} \mid \mathrm{Sn}_{(\mathrm{s})}\right)=-0.14 \mathrm{~V} \end{aligned} $$

What is standard emf of cell containing the two electrodes?