Question

Arrange the following elements in the increasing order of number of unpaired electrons in it.
(A) Sc
(B) Cr
(C) V
(D) Ti
(E) Mn
Choose the correct answer from the options given below:

• A. (C) $<$ (E) $<$ (B) $<$ (A) $<$ (D)
• B. (B) $<$ (C) $<$ (D) $<$ (E) $<$ (A)
• C. (A) $<$ (D) $<$ (C) $<$ (B) $<$ (E)
• D. (A) $<$ (D) $<$ (C) $<$ (E) $<$ (B)

Answer 1

Answer: (D)

(A) $<$ (D) $<$ (C) $<$ (E) $<$ (B)

Answer 2

The electronic configurations and the number of unpaired electrons for each element are as follows:

Sc: $[ \text{Ar} ] 4s^2 3d^1 \quad (1 \text{ unpaired electron})$
Cr: $[ \text{Ar} ] 4s^1 3d^5 \quad (6 \text{ unpaired electrons})$
V: $[ \text{Ar} ] 4s^2 3d^3 \quad (3 \text{ unpaired electrons})$
Ti: $[ \text{Ar} ] 4s^2 3d^2 \quad (2 \text{ unpaired electrons})$
Mn: $[ \text{Ar} ] 4s^2 3d^5 \quad (5 \text{ unpaired electrons})$

Arranging them in increasing order of unpaired electrons, we get:

$\text{Sc (A)} < \text{Ti (D)} < \text{V (C)} < \text{Mn (E)} < \text{Cr (B)}$