Question

If elements with principal quantum number n > 4 were not allowed in nature, then what will be the number of possible elements?

(a) 60

(b) 20

(c) 4

(d) 64

This question was addressed to me in class test.

This interesting question is from Atomic Masses and Composition of Nucleus in chapter Nucleus of Physics – Class 12

Answer 1

Correct option is (a) 60

To explain: Maximum number of electrons in an orbit = 2n^2.

As n > 4 is not allowed, the number of possible elements = 2(1)^2 + 2(2)^2 + 2(3)^2

Number of possible elements = 2(4)^2

Number of possible elements = 60.