1
JEE Main 2025 (Online) 29th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Identify the homoleptic complexes with odd number of $d$ electrons in the central metal :

(A) $\left[\mathrm{FeO}_4\right]^{2-}$

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

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

(D) $\left[\mathrm{CoCl}_4\right]^{2-}$

(E) $\left[\mathrm{Co}\left(\mathrm{H}_2 \mathrm{O}\right)_3 \mathrm{~F}_3\right]$

Choose the correct answer from the options given below :

A

(C) and (E) only

B

(A), (B) and (D) only

C

(B) and (D) only

D

(A), (C) and (E) only

2
JEE Main 2025 (Online) 29th January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The calculated spin-only magnetic moments of $K_3[Fe(OH)_6]$ and $K_4[Fe(OH)_6]$ respectively are :

A

4.90 and 4.90 B.M.

B

4.90 and 5.92 B.M.

C

5.92 and 4.90 B.M.

D

3.87 and 4.90 B.M.

3
JEE Main 2025 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The correct increasing order of stability of the complexes based on $\Delta_0$ value is :

  1. I. $[\text{Mn}(\text{CN})_6]^{3-}$

  2. II. $[\text{Co}(\text{CN})_6]^{4-}$

  3. III. $[\text{Fe}(\text{CN})_6]^{4-}$

  4. IV. $[\text{Fe}(\text{CN})_6]^{3-}$
A

I < II < IV < III

B

IV < III < II < I

C

III < II < IV < I

D

II < III < I < IV

4
JEE Main 2025 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Match List - I with List - II.

List - I (Complex) List - II (Hybridisation & Magnetic characters)
(A) [MnBr4]2- (I) d2sp3 & diamagnetic
(B) [FeF6]3- (II) sp3d2 & paramagnetic
(C) [Co(C2O4)3]3- (III) sp3 & diamagnetic
(D) [Ni(CO)4] (IV) sp3 & paramagnetic

Choose the correct answer from the options given below :

A

(A)-(III), (B)-(I), (C)-(I), (D)-(IV)

B

(A)-(III), (B)-(II), (C)-(III), (D)-(IV)

C

(A)-(IV), (B)-(II), (C)-(I), (D)-(III)

D

(A)-(IV), (B)-(I), (C)-(II), (D)-(III)

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