Statement (I) $\mathrm{Co}^{2+}$ has higher magnetic moment than $\mathrm{Cr}^{3+}$. Statement (II) Ionisation enthalpies of Ce, Pr and $\mathrm{Nd}$ are higher than $\mathrm{Th}, \mathrm{Pa}, \mathrm{U}$. Which of the following is correct?

• A

  Both (l) and (II) are not correct
• B

  Both (I) and (II) are correct
• C

  (l) is correct but (II) is not correct
• Correct answer
  D

  (l) is not correct but (II) is correct

Solution

Statement (I) is not correct, as magnetic moment of $\mathrm{Cr}^{3+}$ is more than of $\mathrm{CO}^{2+}$. But, statement (II) is correct, as I.P. of Ce, Pr and Nd are higher than th, Pa and U. Thus, the correct option is (4).

Hence, the correct answer is option: 'D'.