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

Q: 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

Ans: (A)

Sol: The maximum number of electrons in an orbit = 2n2

If principal quantum number n > 4 were not allowed , then the number of maximum electrons that can be in first four orbits are :

$\large = 2(1)^2 + 2(2)^2 + 2(3)^2 + 2(4)^2$

= 2 + 8 + 18 + 32 = 60

The number of possible elements would be 60