Magnetic moment of Cr^ 2+ is nearest to

$\mathrm{Cr}^{2+}=3 d^4$, No. of unpaired electrons $(n)=4$ Magnetic moment $=\sqrt{(+2)} \mathrm{BM}$ $=\sqrt{4(4+2)}=\sqrt{24}=4.89 \mathrm{BM}$ $\mathrm{Fe}^{2+}=3 d^6$, No. of unpaired electrons $(n)=4$ Magnetic moment $=\sqrt{4(4+2)} \mathrm{BM}$ $=\sqrt{24}=4.89 \mathrm{BM}$ $\mathrm{Mn}^{2+}=3 d^5$, No. of unpaired electrons $(n)=5$ Magnetic moment $=\sqrt{5(5+2)} \mathrm{BM}$ $=\sqrt{35}=5.91 \mathrm{BM}$ $\mathrm{Co}^{2+}=3 d^7$, No. of unpaired electrons $(n)=3$ Magnetic moment $=\sqrt{3(3+2)} \mathrm{BM}$ $=\sqrt{15}=3.87 \mathrm{BM}$ $\mathrm{Ni}^{2+}=3 d^8$, No. of unpaired electrons $(n)=2$ Magnetic moment $=\sqrt{2(2+2)} \mathrm{BM}$ $=\sqrt{\circledast}=2.82 \mathrm{BM}$