Question

How many electrons in an atom may have n=4 and ms=+1/2?

Answer 1

In a atom having ,principal quantum no(n)=4
subshells having value (n-1) are present{I.e. s,p,d,f}
now s subshell can have max. 2 electrons
p can have 6
d can have 10
f can have 14
also, only half no. of max. electrons in a subshell can have m=+1/2
so, 1+3+5+7=16 electrons can have m=+1/2