COMEDK · Chemistry · 23. d and f Block Elements

The metallic ions that have almost same spin only magnetic moment are :
(i) \(\mathrm{Co}^{2+}\)
(ii) \(\mathrm{Mn}^{2+}\)
(iii) \(\mathrm{Cr}^{2+}\)
(iv) \(\mathrm{Cr}^{3+}\)

A \(\text { (i) and (iv) }\)
B \(\text { (i) and (iii) }\)
C \(\text { (i) and (ii) }\)
D \(\text { (iii) and (iv) }\)

Verified Solution

Answer & Solution

Correct Answer

(A) \(\text { (i) and (iv) }\)

Step-by-step Solution

Detailed explanation

The spin-only magnetic moment is calculated using the formula \(\mu = \sqrt{n(n+2)}\) B.M., where \(n\) is the number of unpaired electrons. For \(\mathrm{Co}^{2+}\) (\(Z=27\)): The electronic configuration is \([Ar] 3d^7\). The number of unpaired electrons \(n = 3\). Thus,…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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The metallic ions that have almost same spin only magnetic moment are :(i) \(\mathrm{Co}^{2+}\)(ii) \(\mathrm{Mn}^{2+}\)(iii) \(\mathrm{Cr}^{2+}\)(iv) \(\mathrm{Cr}^{3+}\)

Step-by-step Solution

The metallic ions that have almost same spin only magnetic moment are :
(i) \(\mathrm{Co}^{2+}\)
(ii) \(\mathrm{Mn}^{2+}\)
(iii) \(\mathrm{Cr}^{2+}\)
(iv) \(\mathrm{Cr}^{3+}\)