If the half-cell reaction $A + e^- \to A^-$ has a large negative reduction potential,it follows that

$I_2 + 2e^{-} \to 2I^{-}$; $E^{o} = 0.54 \ V$
$Cl_2 + 2e^{-} \to 2Cl^{-}$; $E^{o} = 1.36 \ V$
$Mn^{3+} + e^{-} \to Mn^{2+}$; $E^{o} = 1.50 \ V$
$Fe^{3+} + e^{-} \to Fe^{2+}$; $E^{o} = 0.77 \ V$
Which of the following is a correct statement?

Standard electrode potential of $Ag^{+}/Ag$ and $Cu^{2+}/Cu$ is $+0.80 \ V$ and $+0.34 \ V$ respectively. These electrodes are joined together by a salt bridge. If:

The standard reduction potential for $Fe^{2+}/Fe$ and $Sn^{2+}/Sn$ electrodes are $-0.44 \ V$ and $-0.14 \ V$ respectively. For the given cell reaction $Fe^{2+} + Sn \to Fe + Sn^{2+}$,the standard $EMF$ is ...............$V$.

The standard reduction potential for $Mg^{2+}/Mg$ is $-2.37 \ V$ and for $Cu^{2+}/Cu$ is $0.337 \ V$. The $E^{\circ}_{cell}$ for the following reaction is $Mg + Cu^{2+} \longrightarrow Mg^{2+} + Cu$

What is standard electrode potential?