Medium MCQ +4 / -1 PYQ · JEE Mains 2025

The correct decreasing order of spin only magnetic moment values (BM) of Cu+, Cu2+, Cr2+ and Cr3+ ions is :

  1. A <p>Cr<sup>3+</sup> &gt; Cr<sup>2+</sup> &gt; Cu<sup>+</sup> &gt; Cu<sup>2+</sup></p>
  2. B <p>Cu<sup>+</sup> &gt; Cu<sup>2+</sup> &gt; Cr<sup>3+</sup> &gt; Cr<sup>2+</sup></p>
  3. C <p>Cr<sup>2+</sup> &gt; Cr<sup>3+</sup> &gt; Cu<sup>2+</sup> &gt; Cu<sup>+</sup></p> Correct answer
  4. D <p>Cu<sup>2+</sup> &gt; Cu<sup>+</sup> &gt; Cr<sup>2+</sup> &gt; Cr<sup>3+</sup></p>

Solution

<p>$\mathrm{Cu}^{+}:[\mathrm{Ar}] 3 \mathrm{~d}^{10}$, Spin only magnetic moment $=0$ B.M.</p> <p>$\mathrm{Cu}^{+2}:[\mathrm{Ar}] 3 \mathrm{~d}^9$, Spin only magnetic moment $=\sqrt{3}$ B.M.</p> <p>$\mathrm{Cr}^{+2}:[\mathrm{Ar}] 3 \mathrm{~d}^4$, Spin only magnetic moment $=\sqrt{24}$ B.M.</p> <p>$\mathrm{Cr}^{+3}:[\mathrm{Ar}] 3 \mathrm{~d}^3$, Spin only magnetic moment $=\sqrt{15}$ B.M.</p> <p>Order of $\mu: \mathrm{Cr}^{+2}>\mathrm{Cr}^{+3}>\mathrm{Cu}^{+2}>\mathrm{Cu}^{+}$</p>

About this question

Subject: Chemistry · Chapter: d and f Block Elements · Topic: Properties of Transition Metals

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