JEE Main · 2025 · Shift-ImediumEC-133

The standard reduction potential values of some of the p-block ions are given below. Predict the one with the strongest…

Electrochemistry · Class 12 · JEE Main Previous Year Question

Question

The standard reduction potential values of some of the p-block ions are given below. Predict the one with the strongest oxidising capacity.

(a) E\ceSn4+/Sn2+∘=+1.15E^\circ_{\ce{Sn^{4+}/Sn^{2+}}} = +1.15 V

(b) E\ceTl3+/Tl∘=+1.26E^\circ_{\ce{Tl^{3+}/Tl}} = +1.26 V

(c) E\ceAl3+/Al∘=−1.66E^\circ_{\ce{Al^{3+}/Al}} = -1.66 V

(d) E\cePb4+/Pb2+∘=+1.67E^\circ_{\ce{Pb^{4+}/Pb^{2+}}} = +1.67 V

Options
  1. a

    \ceSn4+\ce{Sn^{4+}}

  2. b

    \ceTl3+\ce{Tl^{3+}}

  3. c

    \ceAl3+\ce{Al^{3+}}

  4. d

    \cePb4+\ce{Pb^{4+}}

    ✓
Correct Answerd

\cePb4+\ce{Pb^{4+}}

Detailed Solution

Strategy: Oxidizing capacity relates to the tendency of a species to gain electrons (be redu\ced). The species with the highest (most positive) standard reduction potential (Ered∘E^\circ_{ \text{red}}) is the strongest oxidizing agent.

Comparison:

  • (a) \ceSn4+/Sn2+:+1.15 V\ce{Sn^{4+}/Sn^{2+}}: +1.15 \text{ V}
  • (b) \ceTl3+/Tl:+1.26 V\ce{Tl^{3+}/Tl}: +1.26 \text{ V}
  • (c) \ceAl3+/Al:−1.66 V\ce{Al^{3+}/Al}: -1.66 \text{ V}
  • (d) \cePb4+/Pb2+:+1.67 V\ce{Pb^{4+}/Pb^{2+}}: +1.67 \text{ V} (Highest)

Conclusion: Lead(IV) is highly unstable and will strongly tend to redu\ce to Lead(II), especially due to the inert pair effect.

Answer: (d) \cePb4+\boxed{\text{Answer: (d) } \ce{Pb^{4+}}}

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