JEE Chemistry 2025 Question with Solution

Given: We need the metal ion whose electronic configuration is not affected by the nature of the ligand and which gives a violet color in the borax bead test under hot condition.

Find: The correct option.

A metal ion whose electronic configuration remains essentially unaffected by ligand field considerations is expected to have a specially stable configuration such as a half-filled d-subshell. Among the given ions, $\mathrm{Mn}^{2+}$ has configuration $3d^5$, which is half-filled and particularly stable.

From the borax bead test colors given in the solution:

• $\mathrm{Cr}^{3+}$ gives green when hot.
• $\mathrm{Ni}^{2+}$ gives reddish brown.
• $\mathrm{Mn}^{2+}$ gives violet when hot.

Therefore, the ion satisfying both conditions is $\mathrm{Mn}^{2+}$.

The correct option is D.

Given: The required ion must satisfy two conditions:

1. Its electronic configuration is not affected by the nature of the ligand.
2. It gives a violet color in the hot borax bead test.

Find: Which option matches both conditions.

Step 1: Check electronic configuration stability. A half-filled or fully filled d-subshell is especially stable and is least affected in this context by the ligand nature.

Among the options:

• $\mathrm{Ti}^{3+} : d^1$
• $\mathrm{Cr}^{3+} : d^3$
• $\mathrm{Ni}^{2+} : d^8$
• $\mathrm{Mn}^{2+} : d^5$

Step 2: Identify the ion with the most stable configuration. $\mathrm{Mn}^{2+}$ has the half-filled configuration $d^5$, so it matches the first condition.

Step 3: Use the borax bead test color. The violet-colored bead in hot condition is produced by $\mathrm{Mn}^{2+}$.

Conclusion: Both criteria point to $\mathrm{Mn}^{2+}$. Hence, the final answer is Option D.