Question

An $e^{-}$ has magnetic quantum number as $-3$, what is its principal quantum number?

• A. $1$
• B. $2$
• C. $3$
• D. $4$

Answer 1

The correct option is D $4$

An $e^{-}$ has magnetic quantum number as $-3$, its principal quantum number is $4$.

When $m=-3$, $l=3$ $\therefore$ $n=4$
Note: For a given value of n, l can have values 0, 1, 2,....(n$-$1) and m can have values $-l$, ....$-$2,$-$1,0, $+$1, $+$2... $+l$.
For $n=4$, $l$ can have values 0, 1, 2, 3.

For a given value of $l,m$ can have values $-$3,$-$2,$-$1,0, $+$1, $+$2, $+$3.