Ques. 1JEE Main 2025, 28 January (Morning Shift)
The metal ion whose electronic configuration is not affected by the nature of the ligand and which gives a violet colour in non-luminous flame under hot condition in borax bead test is
- Cr3+
- Ti3+
- Ni2+
- Mn2+
Answer
(3) Ni2+
Solution
Octahedral configurations:
Cr3+ (3d3): t2g3; Ti3+ (3d1): t2g1; Ni2+ (3d8): t2g6eg2 — the same with weak and strong field ligands.
Mn2+ (3d5): t2g3eg2 (weak field) or t2g5 (strong field) — affected by the ligand.
Borax bead test in the non-luminous (oxidising) flame: Ni gives a violet bead when hot (reddish-brown when cold); Cr gives a green bead; Mn gives an amethyst bead both hot and cold.
The ion is Ni2+.
Answer: (3)