JEE Main 2025 Apr 8 Shift 2, Chemistry Q11: d-Block Elements

JEE Main2025Apr 8, Shift 2Chemistry

The correct decreasing order of spin only magnetic moment values (BM) of Cu $^{+}$ , Cu $^{2 +}$ , Cr $^{2 +}$ and Cr $^{3 +}$ ions is:

Solution

Cu $^{+}$ has configuration $[A r] 3 d^{10}$ with no unpaired electrons, giving a spin-only moment of 0 BM.

Cu $^{2 +}$ has configuration $[A r] 3 d^{9}$ with one unpaired electron, giving $μ = 3 \approx 1.73$ BM.

Cr $^{2 +}$ has configuration $[A r] 3 d^{4}$ with four unpaired electrons, giving $μ = 24 \approx 4.90$ BM.

Cr $^{3 +}$ has configuration $[A r] 3 d^{3}$ with three unpaired electrons, giving $μ = 15 \approx 3.87$ BM.

Ordering from highest to lowest magnetic moment: Cr $^{2 +}$ > Cr $^{3 +}$ > Cu $^{2 +}$ > Cu $^{+}$ , matching option (3).

Concept behind this question

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