1
JEE Main 2025 (Online) 23rd January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The d-electronic configuration of an octahedral Co (II) complex having magnetic moment of 3.95 BM is:

A
$e^4 t_2^3$
B
$\mathrm{t}_{2 \mathrm{~g}}{ }^6 \mathrm{e}_{\mathrm{g}}{ }^1$
C
$\mathrm{t}_{2 \mathrm{~g}}{ }^5 \mathrm{e}_{\mathrm{g}}{ }^2$
D
$t_{2 g^3}^3 e_g^0$
2
JEE Main 2025 (Online) 23rd January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The complex that shows Facial - Meridional isomerism is :

A
$\left[\mathrm{Co}(\mathrm{en})_2 \mathrm{Cl}_2\right]^{+}$
B
$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3 \mathrm{Cl}_3\right]$
C
$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4 \mathrm{Cl}_2\right]^{+}$
D
$\left[\mathrm{Co}(\mathrm{en})_3\right]^{3+}$
3
JEE Main 2025 (Online) 22nd January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The correct order of the following complexes in terms of their crystal field stabilization energies is :

A
$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4\right]^{2+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{2+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}<\left[\mathrm{Co}(\mathrm{en})_3\right]^{3+}$
B
$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4\right]^{2+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{2+}<\left[\mathrm{Co}(\mathrm{en})_3\right]^{3+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$
C
$\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{2+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4\right]^{2+}<\left[\mathrm{Co}(\mathrm{en})_3\right]^{3+}$
D
$\left[\mathrm{Co}(\mathrm{en})_3\right]^{3+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{2+}<\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_4\right]^{2+}$
4
JEE Main 2025 (Online) 22nd January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Identify the homoleptic complex(es) that is/are low spin.

(A) $\left[\mathrm{Fe}(\mathrm{CN})_5 \mathrm{NO}\right]^{2-}$

(B) $\left[\mathrm{CoF}_6\right]^{3-}$

(C) $\left[\mathrm{Fe}(\mathrm{CN})_6\right]^{4-}$

(D) $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$

(E) $\left[\mathrm{Cr}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$

Choose the correct answer from the options given below :

A
(C) and (D) only
B
(C) only
C
(A) and (C) only
D
(B) and (E) only
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