Which of the following is the strongest oxidising agent?

Standard potential of electrode reaction $Cu^{2+}_{(aq)} + 2e^{-} \rightarrow Cu_{(s)}$ is $+0.34 \ V$. What is the standard potential of the reaction $2Cu_{(s)} \rightarrow 2Cu^{2+}_{(aq)} + 4e^{-}$?

If the standard reduction potentials of $Zn$, $Ni$, and $Fe$ are $-0.76 \text{ V}$, $-0.23 \text{ V}$, and $-0.44 \text{ V}$ respectively, determine the electrodes $X$ and $Y$ for the reaction $X(s) + Y^{+2}_{(aq)} \rightarrow X^{+2}_{(aq)} + Y(s)$ to be spontaneous.

For the cell reaction $Mg_{(s)} + Zn^{2+}_{(aq)} (1M) \rightarrow Zn_{(s)} + Mg^{2+}_{(aq)} (1M)$,the $emf$ is $1.60 \ V$. The $E$ of the cell is ........ $V$.

The oxidation potentials of $Zn, Cu, Ag, H_2$ and $Ni$ are $0.76, -0.34, -0.80, 0$ and $0.25 \ V$ respectively. Which reaction provides the maximum voltage?

Standard electrode potential for $Sn^{4+}/Sn^{2+}$ couple is $+0.15 \ V$ and that for the $Cr^{3+}/Cr$ couple is $-0.74 \ V.$ These two couples in their standard state are connected to make a cell. The cell potential will be ........ $V$