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JEE Mains · Chemistry · STD 12 - 2. Electrochemistry

The standard reduction potentials at \(298 \mathrm{~K}\) for the following half cells are given below : \(\mathrm{Cr}_2 \mathrm{O}_7{ }^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}, \mathrm{E}^{\circ}=1.33 \mathrm{~V}\) \(\mathrm{Fe}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe}  \mathrm{E}^{\circ}=-0.04 \mathrm{~V}\) \(\mathrm{Ni}^{2+}(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow \mathrm{Ni}  \mathrm{E}^{\circ}=-0.25 \mathrm{~V}\) \(\mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Ag} \mathrm{E}^{\circ}=0.80 \mathrm{~V}\) \(\mathrm{Au}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Au} \mathrm{E}^{\circ}=1.40 \mathrm{~V}\) 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 _______.

  1. A \(5\)
  2. B \(6\)
  3. C \(2\)
  4. D \(3\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(3\)

Step-by-step Solution

Detailed explanation

\(\mathrm{Fe}, \mathrm{Ni}, \mathrm{Ag}\) will be oxidized due to lower \(S.R.P\).
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