How many sub-shells are associated with n=4 ? How many electrons will be present in the sub-shell having ms value of -1/2 for n=4 ?

Explanation

For `n=4,` Four sub-sheels namely `4s, 4p, 4d and 4f ` are possible.
Total number of electrons present in these sub shells having `m_(s)` value of `-1//2` is 16.