If elements with principal quantum number `ngt 4` were not allowed in nature, the number of possible elements would be:

Correct Answer - B
If all the elements having `ngt4` are removed the number of elements that will be present in the periodic table are calculated as
n=1 represents K shell and the number of elements having K shell =2 [ in accoredance with `2n^(2)`]
n=2 , repreents L shell and the number of elements having L shell =8
n=3 represent M shell and the number of elements having M shell =18
n=4 represents N shell and the number of elements having N shell =32
So, the number of elelments of elements having `nlt5` are
`" " 2+8+18+32=60`