Question

In an atom, the total number of electrons having quantum numbers $n=4,|m_l|=1$ and $m_s=-\frac{1}{2}$ is :

• A. 6
• B. 12
• C. 13
• D. 10

Answer 1

The correct option is A 6

Given,
$|m_l|=1$ means $m_l$ can be +1 and -1.
Since n = 4, the possible values of `$l$' are 0,1,2 and 3.
For, $l$=0 the orbitals of required $m_l$ value are not possible.

For the rest of the sub shells we will get a total of 6 orbitals having $m_l$ values +1 and -1.

So 6 orbitals can accomodate maximum of 12 electrons according to Pauli's exclusion principle. Since we are considering only $+\frac{1}{2}$ spin, thus we will get 6 electrons only.