The standard reduction potential at 298 K for the following half cells are given below:
$\begin{array}{l}{\mathrm{NO}}_3^{-}+4{\mathrm{H}}^{+}+3{\mathrm{e}}^{-}\to \mathrm{NO}\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}{\mathrm{E}}^0=0.97\mathrm{V}\\ {\mathrm{V}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{e}}^{-}\to \mathrm{V}{\mathrm{E}}^0=-1.19\mathrm{V}\\ {\mathrm{Fe}}^{3+}\left(\mathrm{aq}\right)+3{\mathrm{e}}^{-}\to \mathrm{Fe}{\mathrm{E}}^0=-0.04\mathrm{V}\\ {\mathrm{Ag}}^{+}\left(\mathrm{aq}\right)+{\mathrm{e}}^{-}\to \mathrm{Ag}\left(\mathrm{s}\right){\mathrm{E}}^0=0.80\mathrm{V}\\ {\mathrm{Au}}^{3+}\left(\mathrm{aq}\right)+3{\mathrm{e}}^{-}\to \mathrm{Au}\left(\mathrm{s}\right){\mathrm{E}}^0=1.40\mathrm{V}\end{array}$
The number of metal(s) which will be oxidized by NO₃^- in aqueous solution is _____