Question

The valence electrons of magnesium is different in ........... quantum number.

• A. $m$
• B. $n$
• C. $l$
• D. $s$

Answer 1

The correct option is D $s$

The configuration of magnesium is $1s^{2}2s^{2}2p^{6}3s^2$.
The outermost electron is in s orbital and is paired.
Therefore, for the two electrons in 3s orbital, only s, spin quantum number is different.