UPSEE 2019 Solved Paper

Magnetic moment (µ) is calculated as follows:
µ=√n(n+2).BM
where, n= number of unpaired electrons.
(d) CO2+=6+8−2=12 electrons.
Thus, has 4 electrons in 2p-subshell with 2-unpaired electron.
∴µ=√2(2+2)=√8
Hence, Mn2+ has highest magnetic moment and option (b) is the correct answer.