What is to be done to determine the potential of any half cell?

The standard reduction potentials at $298 \ K$ for the following half-cell reactions are given below:
$Zn^{2+}_{(aq)} + 2e^{-} \rightleftharpoons Zn_{(s)} : -0.762 \ V$
$Cr^{3+}_{(aq)} + 3e^{-} \rightleftharpoons Cr_{(s)} : -0.74 \ V$
$2H^{+}_{(aq)} + 2e^{-} \rightleftharpoons H_{2(g)} : 0.00 \ V$
$Fe^{3+}_{(aq)} + e^{-} \rightleftharpoons Fe^{2+}_{(aq)} : 0.77 \ V$
Which one of the following is the strongest reducing agent?

If the reduction potential is more,then

The correct order of reduction potentials of the following pairs is
$A.$ $Cl_2 / Cl^{-}$
$B.$ $I_2 / I^{-}$
$C.$ $Ag^{+} / Ag$
$D.$ $Na^{+} / Na$
$E.$ $Li^{+} / Li$
Choose the correct answer from the options given below.

Given the standard electrode potentials,what is the standard electrode potential for the reaction $Fe^{3+}_{(aq)} + e^{-} \rightarrow Fe^{2+}_{(aq)}$ in $V$?
$Fe^{3+}_{(aq)} + 3e^{-} \rightarrow Fe_{(s)}$ ; $E^o = -0.036 \ V$
$Fe^{2+}_{(aq)} + 2e^{-} \rightarrow Fe_{(s)}$ ; $E^o = -0.440 \ V$

Which among the following species is reduced by tin easily?