Question

If elements with principal quantum number n > 4 were not allowed in nature, the number of possible elements would be

• A. 60
• B. 32
• C. 4
• D. 64

Answer 1

The correct option is A 60

The maximum number of electrons in an orbit is $2n^2$
Each element differs from other from number of electrons.
Maximum value of n = 4
So possible (maximum) no. of elements
$N=2\times 1^2+2\times 2^2+2\times 3^2+2\times 4^2=2+8+18+32=60$