Question

An element with atomic number 21 is a:

• A. halogen
• B. representative element
• C. transition element
• D. alkali element

Answer 1

The correct option is C transition element

An element with atomic number 21 is having the following electronic configuration = $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^1$

Based on the electronic configuration it is clear that the element belongs to transition elements and the name of the element is Scandium.

Hence, option C is correct.