Acetic acid has $K _{ a }=1.8 \times 10^{-5}$ while formic acid has $K _{ a }=2.1 \times 10^{-4}$. What would be the magnitude of the emf of the cell
$Pt \left( H _{2}\right)\left|\begin{array}{c}0.1 M \text { acetic acid }+ \\ 0.1 M \text { sodium acetate }\end{array}\right|\left|\begin{array}{cc}0.1 M \text { formic acid }+ \\ 0.1 M \text { sodium formate }\end{array}\right| Pt \left( H _{2}\right)$ at $25^{\circ} C ?$
(A) $0.032$ volt
(B) $0.063$ volt
(C) $0.0456$ volt
(D) $0.055$ volt
