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

Maximum value of n = 4

So possible (maximum) no. of elements

$N = 2 \times 1^{2} + 2 \times 2^{2} + 2 \times 3^{2} + 2 \times 4^{2} = 2 + 8 + 18 + 32 = 60$