Given below are two statements : Statement I : The Eo value for Ce^4+ / Ce^3+ is + 1.74 V. Statement II : Ce is more stable in Ce^4+ state than Ce^3+ state. In the light of the above statements, choose the most appropriate answer from the options given below :

Statement I is correct but statement II is incorrect

Statement I is incorrect but statement II is correct

Both statement I and statement II are correct

Both statement I and statement II are incorrect

D and F Block Elements PYQ — JEE Main 2021 · 16 Mar · Shift 1 · Q5 with Solution

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Correct answer: D

Evaluate Statement I

For lanthanoids, the standard reduction potential for the couple $Ce^{4+} + e^- \rightarrow Ce^{3+}$ is known to be $E^\circ = +1.74\,\text{V}$

Hence, Statement I is correct.
Evaluate Statement II

Cerium has electronic configuration: $Ce: [Xe]4f^1 5d^1 6s^2$

Common oxidation states are $+3$ and $+4$ .
- $Ce^{3+}$ has configuration: $[Xe]4f^1$
- $Ce^{4+}$ has configuration: $[Xe]$
Although $Ce^{4+}$ attains a noble-gas-like configuration and is important in some compounds, in aqueous/redox terms the very high positive value $E^\circ(Ce^{4+}/Ce^{3+}) = +1.74\,\text{V}$ shows that $Ce^{4+}$ is strongly prone to get reduced to $Ce^{3+}$ .

Therefore, $Ce^{3+}$ is more stable than $Ce^{4+}$ in general redox sense, and Statement II is incorrect.
Conclusion
- Statement I: Correct
- Statement II: Incorrect
Therefore, the correct option is: $\boxed{\text{D}}$

View written solutionFree

Correct answer: D

Evaluate Statement I

For lanthanoids, the standard reduction potential for the couple $Ce^{4+} + e^- \rightarrow Ce^{3+}$ is known to be $E^\circ = +1.74\,\text{V}$

Hence, Statement I is correct.
Evaluate Statement II

Cerium has electronic configuration: $Ce: [Xe]4f^1 5d^1 6s^2$

Common oxidation states are $+3$ and $+4$ .
- $Ce^{3+}$ has configuration: $[Xe]4f^1$
- $Ce^{4+}$ has configuration: $[Xe]$
Although $Ce^{4+}$ attains a noble-gas-like configuration and is important in some compounds, in aqueous/redox terms the very high positive value $E^\circ(Ce^{4+}/Ce^{3+}) = +1.74\,\text{V}$ shows that $Ce^{4+}$ is strongly prone to get reduced to $Ce^{3+}$ .

Therefore, $Ce^{3+}$ is more stable than $Ce^{4+}$ in general redox sense, and Statement II is incorrect.
Conclusion
- Statement I: Correct
- Statement II: Incorrect
Therefore, the correct option is: $\boxed{\text{D}}$