Question:
Given below are two statements:
Statement $\mathrm{I}$ : The $\mathrm{E}^{\circ}$ value of $\mathrm{Ce}^{4+} / \mathrm{Ce}^{3+}$ is $+1.74 \mathrm{~V}$
Statement II : Ce is more stable in $\mathrm{Ce}^{4+}$ state than $\mathrm{Ce}^{3+}$ state.
In the light of the above statements, choose the most appropriate answer from the options given below:
Correct Option: , 4
Solution:
The $\mathrm{E}^{\circ}$ value for $\mathrm{Ce}^{4+} / \mathrm{Ce}^{3+}$ is $+1.74 \mathrm{~V}$ because the most stable oxidation state of lanthanide series elements is $+3$. It means $\mathrm{Ce}^{3+}$ is more stable than $\mathrm{Ce}^{4+} .$