JEE Main 2024 — 9 April, Shift 1 — Question 78

The standard reduction potentials at 298 K for the following half cells are given below :

$\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_{2} \mathrm{O}, \mathrm{E}^{\circ}=1.33 \mathrm{~V}$

$\mathrm{Fe}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} \quad \mathrm{E}^{\circ}=-0.04 \mathrm{~V}$

$\mathrm{Ni}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{Ni} \quad \mathrm{E}^{\circ}=-0.25 \mathrm{~V}$

$\mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Ag} \quad \mathrm{E}^{\circ}=0.80 \mathrm{~V}$

$\mathrm{Au}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Au} \quad \mathrm{E}^{\circ}=1.40 \mathrm{~V}$

Consider the given electrochemical reactions, The number of metal(s) which will be oxidized be $\mathrm{Cr}_{2} \mathrm{O}_{7}{ }^{2-}$, in aqueous

solution is $\qquad$