NEET 2025 · ChemistryMagnetismPrevious Year Question
Given below are two statements: Statement I: Ferromagnetism is considered as an extreme form of paramagnetism. Statement II: The number of unpaired electrons in a \ce{Cr^2+} ion (Z = 24) is the same as that of a \ce{Nd^3+} ion (Z = 60). In the light of the above statements, choose the correct answer from the options given below:
- A.(a) Statement I is true but Statement II is false✓
- B.(b) Statement I is false but Statement II is true
- C.(c) Both Statement I and Statement II are true
- D.(d) Both Statement I and Statement II are false
Correct Answer
(A) (a) Statement I is true but Statement II is false
Solution & Explanation
\textbf{Answer:} (a) Statement I is true but Statement II is false \textbf{Solution:} Statement I is correct: in ferromagnetic substances the unpaired-electron spins of neighbouring atoms align in the same direction, giving a very strong magnetisation. This is regarded as an extreme (cooperative) form of paramagnetism. Statement II is wrong. \ce{Cr^2+} is \ce{3d^4}, which has 4 unpaired electrons. \ce{Nd^3+} is \ce{[Xe] 4f^3}, which has only 3 unpaired electrons. The counts (4 vs 3) are not the same. Hence Statement I is true but Statement II is false.
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