### Q.31:- How many electrons in an atom may have the following quantum numbers?

(a) n = 4, m_{s} = –½ (b) n = 3, *l* = 0

**Answer:-**

(i) The total number of electrons in n is given by 2n^{2}

n=4, Number of electrons = 2×4^{2 }= 32

Half of 32 electrons will have spin quantum number m_{s} = –½ i.e. 16 electrons

(ii) n=3 and *l*=0 means it is 3s orbital which can have only 2 electrons.