How many electron in an atom may have the following quantum number ?
a. `n = 4, m_(s) = -(1)/(2)`
b. `n = 3,l = 0`

Explanation

(a) Total number of electrons in an atom for a value of `n = 2n^(2)`
`therefore ` For n = 4
Total number of electrons = `2(4)^(2)`
= 32
The given element has a fully filled orbital as
`1 s^(2) 2 s^(2) 2 p^(6) 3s^(2) 3p^(6) 4s^(2) 3d^(10)`
Hence , all the electrons are paired .
`therefore ` Number of electrons (having n = 4 and `m_(s) = (1)/(2)`) = 16
(b) n = 3, l = 0 indicates that the electrons are present in the 3s orbital. Therefore, the number of electrons having n = 3 and l = 0 is 2.