Question

Which of the following species has (have) five unpaired electrons?

• A. Cs
• B. Mn
• C. Mn${}^{2+}$
• D. Fe${}^{2+}$

Answer 1

Answer: (B), (C)

Mn
Mn${}^{2+}$

$Mn=1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{5}4s^2$

$M{n}^{2+}=1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^5$

Both Mn and $M{n}^{2+}$ have five unpaired electrons because the two electrons removed from $M{n}^{2+}$ is from 4s orbital
Hence, options B & C are correct.