Number of complexes from the following with even number of unpaired "d" electrons is ____. [V(H2O)6]3+,[Cr(H2O)6]2+,[Fe(H2O)6]3+, [Ni(H2O)6]3+,[Cu(H2O)6]2+ [Given atomic numbers : V=23,Cr=24,Fe=26, Ni=28,Cu=29]
(A)2✓ Correct
(B)4
(C)5
(D)1
Answer: (A)
Solution
Number of unpaired d electrons (all high-spin aqua complexes):
[V(H2O)6]3+: V3+d2⇒n=2 (even).
[Cr(H2O)6]2+: Cr2+d4⇒n=4 (even).
[Fe(H2O)6]3+: Fe3+d5⇒n=5 (odd).
[Ni(H2O)6]3+: Ni3+d7⇒n=3 (odd).
[Cu(H2O)6]2+: Cu2+d9⇒n=1 (odd).
Complexes with an even number of unpaired electrons: 2 ⇒ option A.
JEE Main · 2024 · 04 Apr 2024 · Shift 1 · Single correct option