Question

Given below are two statements :

Statement I : The E^o value for Ce⁴⁺ / Ce³⁺ is + 1.74 V.

Statement II : Ce is more stable in Ce⁴⁺ state than Ce³⁺ state.

In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Statement I is incorrect but statement II is correct
• B. Both statement I and statement II are correct
• C. Both statement I and statement II are incorrect
• D. Statement I is correct but statement II is incorrect

Hint:

\(E^\circ(\mathrm{Ce^{4+}/Ce^{3+}}) = +1.74\) V is very positive, so Ce(IV) is a strong oxidant and Ce(III) is the more stable state.

Answer 1

The Correct Option is D

Statement I: the standard electrode potential of \(\mathrm{Ce^{4+}/Ce^{3+}}\) is \(+1.74\ \mathrm{V}\), the accepted value, so Statement I is correct.
Statement II: although \(\mathrm{Ce^{4+}}\) has the noble-gas configuration \([\mathrm{Xe}]\), the large positive \(E^\circ\) shows that \(\mathrm{Ce^{4+}}\) readily gains an electron to become \(\mathrm{Ce^{3+}}\). It is a strong oxidising agent and \(\mathrm{Ce^{3+}}\) is the more stable state in aqueous solution, so Statement II is incorrect.
Answer: (4) Statement I is correct but statement II is incorrect