TS EAMCET · Chemistry · d and f Block Elements

Among the following the incorrect statement about transition metals is

A \(\mathrm{Cr}\), Mo and \(\mathrm{W}\) have high melting points
B With increase in number of unpaired electrons melting point increases
C \(\mathrm{Mn}^{3+}\) is more stable than \(\mathrm{Mn}^{2+}\)
D They show variable oxidation states

Verified Solution

Answer & Solution

Correct Answer

(C) \(\mathrm{Mn}^{3+}\) is more stable than \(\mathrm{Mn}^{2+}\)

Step-by-step Solution

Detailed explanation

\(\mathrm{Mn}=[\mathrm{Ar}] 3 \mathrm{~d}^5 4 \mathrm{~s}^2\) \[ \mathrm{Mn}^{2+}=[\mathrm{Ar}] 3 \mathrm{~d}^5 \text { and } \mathrm{Mn}^{3+}=[\mathrm{Ar}] 3 \mathrm{~d}^4 \] Thus, the half-filled configuration of \(\mathrm{Mn}^{2+}\) leads to its greater stability.

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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