JEE Main 2021ChemistryCoordination CompoundsMediumNumerical

JEE Main 2021 — Coordination Compounds Question with Solution

JEE Main 2021 (20 Jul Shift 1)

Question

The spin-only magnetic moment value for the complex Co(CN)64- is...... BM. (nearest integer value)
[At. no. of Co=27]

Enter your answer

Show full solutionCorrect answer: 2
Correct answer
2

Step-by-step explanation

Co(CN)64-
x+6×(-1)=-4
x=+2
Co2+:[Ar]3 d7 and CN- is a strong field ligand which can pair electron of central atom.

It has one unpaired electron (n) in 4 d-subshell. So spin only magnetic moment (μ)=
n(n+2)B·M
where n= number of unpaired electrons.
μ=3 B.M
μ=1.73 BM ≃2 BM

Practice this on the real CBT interface

Solve this JEE Main question (and the rest of the Coordination Compounds chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.

Solve interactively →

About this question

This is a previous-year question from JEE Main 2021, covering the Coordination Compounds chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.