Question

Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d⁵. What is its atomic number?
(a) 25
(b) 26
(c) 27
(d) 24

Answer 1

X^3+ = [Ar]3d^5

The above element is in +3 oxidation state, the meaning is that it need 3 election to achieve ground state.

Therefore

X = [Ar]3d^8

Atomic number of Art is 18

Atomic number of X = 18+8 =26

Hope you understand