Question

An element-X has mass number 40 and contains 21 neutrons in its atom. The group of the periodic table does it belong is (A) Group 1 (B) Group 4 (C) Group 2 (D) Group 3

plz give an explanation​

Answer 1

Answer:

Group 1

Mass number=40

No. of neutrons=21

So, Atomic number= Mass number - No. of neutrons= 40-21= 19

So, the element is Potassium.

Electronic configuration= 2,8,8,1

Outermost orbit contains 1 electron.So, it belongs to Group 1.