KCET · Chemistry · d and f Block Elements

Identify the set of paramagnetic ions among the following.

A \(\mathrm{V}^{2+}, \mathrm{Co}^{2+}, \mathrm{Ti}^{4+}\)
B \(\mathrm{Ni}^{2+}, \mathrm{Cu}^{2+}, \mathrm{Zn}^{2+}\)
C \(\mathrm{Ti}^{2+}, \mathrm{Cu}^{2+}, \mathrm{Mn}^{3+}\)
D \(\mathrm{Sc}^{3+}, \mathrm{Ti}^{3+}, \mathrm{V}^{3+}\)

Verified Solution

Answer & Solution

Correct Answer

(C) \(\mathrm{Ti}^{2+}, \mathrm{Cu}^{2+}, \mathrm{Mn}^{3+}\)

Step-by-step Solution

Detailed explanation

Out of the given four options, the following set of ions is paramagnetic : \(\mathrm{Ti}^{2+}, \mathrm{Cu}^{2+}, \mathrm{Mn}^{3+}\) \(\mathrm{Ti} \rightarrow 4 s^{2}, 3 d^{2}\) (ground state) \(\mathrm{Ti}^{2+} \rightarrow 3 d^{2} \rightarrow\) 2 unpaired electrons.
\(\mathrm{Cu} \rightarrow 4 s^{1}, 3 d^{10}\) (ground state) \(\mathrm{Cu}^{2+} \rightarrow 3 d^{9} \rightarrow\) 1 unpaired electrons.
\(\mathrm{Mn} \rightarrow 4 s^{2}, 3 d^{5}\) (ground state) \(\mathrm{Mn}^{3+} \rightarrow 3 d^{4} \rightarrow\) 4 unpaired electrons.
A substance is called paramagnetic if it contains at least one unpaired electron.

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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