$($Q$4)$ Given that $E$ cell $=3\mathrm{.}20V$ for the reaction

$2Na(inHg)+C{l}_2(g)2N{a}^{+}(aq)+2C{l}^{-}(aq)$

What is $E$ for the reduction $2N{a}^{+}(aq)+2e^{-}2Na($in $\{$:$Hg)?$