1
JEE Main 2026 (Online) 22nd January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Consider the transition metal ions $\mathrm{Mn}^{3+}, \mathrm{Cr}^{3+}, \mathrm{Fe}^{3+}$ and $\mathrm{Co}^{3+}$ and all form low spin octahedral complexes. The correct decreasing order of unpaired electrons in their respective d-orbitals of the complexes is

A

$\mathrm{Cr}^{3+}>\mathrm{Mn}^{3+}>\mathrm{Fe}^{3+}>\mathrm{Co}^{3+}$

B

$\mathrm{Mn}^{3+}>\mathrm{Fe}^{3+}>\mathrm{Co}^{3+}>\mathrm{Cr}^{3+}$

C

$\mathrm{Fe}^{3+}>\mathrm{Co}^{3+}>\mathrm{Mn}^{3+}>\mathrm{Cr}^{3+}$

D

$\mathrm{Cr}^{3+}>\mathrm{Fe}^{3+}>\mathrm{Co}^{3+}>\mathrm{Mn}^{3+}$

2
JEE Main 2026 (Online) 22nd January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

A first row transition metal $(\mathrm{M})$ does not liberate $\mathrm{H}_2$ gas from dilute HCl .1 mol of aqueous solution of $\mathrm{MSO}_4$ is treated with excess of aqueous KCN and then $\mathrm{H}_2 \mathrm{~S}(\mathrm{~g})$ is passed through the solution. The amount of MS (metal sulphide) formed from the above reaction is $\_\_\_\_$ mol.

A

1

B

2

C

0

D

3

3
JEE Main 2026 (Online) 21st January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Given below are two statements :

Statement I : Crystal Field Stabilization Energy (CFSE) of [Cr(H2O)6]2+ is greater than that of [Mn(H2O)6]2+.

Statement II : Potassium ferricyanide has a greater spin-only magnetic moment than sodium ferrocyanide.

In the light of the above statements, choose the correct answer from the options given below :

A

Statement I is true but Statement II is false

B

Both Statement I and Statement II are true

C

Both Statement I and Statement II are false

D

Statement I is false but Statement II is true

4
JEE Main 2026 (Online) 21st January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Given below are two statements :

Statement I : Among $\left.\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+},\left[\mathrm{Ni}(\mathrm{en})_3\right)\right]^{2+},\left[\mathrm{Ni}\left(\mathrm{NH}_3\right)_6\right]^{2+}$ and $\left[\mathrm{Mn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$, $\left[\mathrm{Mn}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{2+}$ has the maximum number of unpaired electrons.

Statement II : The number of pairs among $\left\{\left[\mathrm{NiCl}_4\right]^{2-},\left[\mathrm{Ni}(\mathrm{CO})_4\right]\right\},\left\{\left[\mathrm{NiCl}_4\right]^{2-},\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}\right\}$ and $\left\{\left[\mathrm{Ni}(\mathrm{CO})_4\right],\left[\mathrm{Ni}(\mathrm{CN})_4\right]^{2-}\right\}$ that contain only diamagnetic species is two.

In the light of the above statements, choose the correct answer from the options given below :

A

Statement I is false but Statement II is true

B

Both Statement I and Statement II are false

C

Both Statement I and Statement II are true

D

Statement I is true but Statement II is false

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