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

Answer: (A)

60

Answer 2

The maximum number of electrons in an orbit are $2n^2$. If
$n > 4$, is not allowed, then the number of maximum electrons
that can be in first four orbit are :
$2 (1)^2 + 2(2)^2 + 2(3)^2 + 2(4)^2 = 2 + 8 + 18 + 32 = 60$
Therefore, possible e' ments can be 60.