Question

The fourth, fifth and sixth periods are long periods and contain …………… 

(A) 18, 18 and 36 

(B) 18, 28 and 32 

(C) 18, 15 and 31 

(D) 18, 18 and 32

Answer 1

Correct option is: (D) 18, 18 and 32

First, second, third, fourth, fifth and sixth periods contain 2, 8, 8, 18, 18, 32 elements respectively. While seventh periods is incomplete

Hence, fourth, fifth and sixth period contain 18, 18, 32 element respectively.

Answer 2

(D) 18, 18 and 32