Question

The pair of ions having same electronic configuration is __________.

• A. ${\mathrm{Cr}}^{3+},{\mathrm{Fe}}^{3+}$
• B. ${\mathrm{Fe}}^{3+},{\mathrm{Mn}}^{2+}$
• C. ${\mathrm{Fe}}^{3+},{\mathrm{Co}}^{3+}$
• D. ${\mathrm{Sc}}^{3+},{\mathrm{Cr}}^{3+}$

Answer 1

The correct option is B

${\mathrm{Fe}}^{3+},{\mathrm{Mn}}^{2+}$

The explanation for the correct option

(B)${\mathrm{Fe}}^{3+},{\mathrm{Mn}}^{2+}$

Electronic configuration

• The distribution of electrons into orbitals of an atom is called its electronic configuration.

Electronic configuration of ${\text{Fe}}^{\text{3+}}$

• Electronic configuration of $\text{Fe}$ is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^6$.
• Three electrons must be released for ${\text{Fe}}^{\text{3+}}$.
• So, the electronic configuration of ${\text{Fe}}^{\text{3+}}$ is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^5$.

Electronic configuration of ${\mathrm{Mn}}^{2+}$

• Electronic configuration of $\text{Mn}$ is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^5$.
• Two electrons must be released for ${\text{Mn}}^{2+}$.
• So, the electronic configuration of ${\text{Mn}}^{2+}$ is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^5$.

So, pair of ions having the same electronic configuration is ${\mathrm{Fe}}^{3+},{\mathrm{Mn}}^{2+}$.

The explanation for the incorrect options

• ${\mathrm{Cr}}^{3+},{\mathrm{Fe}}^{3+}$:-The electronic configuration of ${\mathrm{Cr}}^{3+}$ is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^3$.
• The electronic configuration of ${\text{Fe}}^{\text{3+}}$ is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^5$.
• ${\mathrm{Fe}}^{3+},{\mathrm{Co}}^{3+}$:-The electronic configuration of ${\text{Co}}^{\text{3+}}$ is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^6$.
• ${\mathrm{Sc}}^{3+},{\mathrm{Cr}}^{3+}$: The electronic configuration of ${\text{Sc}}^{\text{3+}}$ is $1s^{2}2s^{2}2p^{6}3s^{2}3p^6$.
• Hence. options (A), (C), and (D) are incorrect.

Hence, option(B) is correct. The pair of ions having the same electronic configuration is ${\mathrm{Fe}}^{3+},{\mathrm{Mn}}^{2+}$.