\(2{H_2}_{(g)} + 4O{H^ - }_{(aq)} \to 4{H_2}{O_{(l)}} + 4{e^ - }\)
\(\underline {{O_2}_{(g)} + 2{H_2}{O_{(l)}} + 4{e^ - } \to 4O{H^ - }_{(aq)}} \)
Overall reaction \(=\,2{H_2}_{(g)} + {O_{2(g)}} \to 2{H_2}{O_{(l)}}\)
the net reaction is the same as burning (Combustion) of hydrogen to form water.
$H_3PO_4 + OH^- \rightarrow H_2PO_4^- + H_2O$ ;
$H_3PO_4 + 2OH^- \rightarrow HPO_4^{2-} + 2H_2O$ ;
$H_3PO_4 + 3OH^- \rightarrow PO_4^{3-} + 3H_2O$
$Zn | Zn ^{2+}(0.1\, M ) \| Ag ^{+}(0.01 \,M )| Ag$
[આપેલ $: E_{Z n^{+2}/Z_{n}}^{0}=-0.76 \,V ; E _{A g^{+} / A_{ g }}^{0}=+0.80 \,V ; \frac{2.303 RT }{ F }=0.059$]