Question

If $n=3,l=0$ and $m=0,$ then atomic number is:

• A. 12 or 13
• B. 13 or 14
• C. 10 or 11
• D. 11 or 12

Answer 1

Answer: (D)

The values of quantum number will give idea about the last subshell of element. From that value we can find the atomic number of element. $n=3$ means 3 rd shell
$\begin{array}{c}l=0\\ m=0\end{array}\}$
It means it is $3$ subshell which can have $1$ or $2$ electrons.
$\therefore$ Configuration of element is $1s^2,2s^2,2p^6,3s^{1-2}$
$\therefore$ Atomic no. is $11$ or $12$