electron configuration of Mg is - [Ne] 3s²
Mg²⁺ ion is formed after the two outer shell electrons are removed and the new configuration is [Ne]
options given and their respective electron configurations are as follows
A. Na⁺ - [Ne]
B. Ca²⁺ - [Ar]
C. S²⁻ - [Ar]
D. Cl⁻ - [Ar]
the ion with same electron configuration as Mg²⁺ is Na⁺
answer is A . Na⁺