The EMF of cell Hg/mercurous nitrate (0.01M)$\parallel$ mercurous nitrate (0.1M)/Hg was found to be 0.0295V at $25^{\large\circ}C$ .Then molecular formula of mercurous nitrate is

Question

$\begin{array}{1 1}(a)\;Hg(NO_3)_2\\(b)\;Hg(NO_3)\\(c)\;Hg_2(NO_3)_2\\(d)\;None\end{array}$