Question

A nucleus emits one α-particle and forms a new nucleus. The mass and charge of the new nucleus is changed in one of the following way 

(a) mass is reduced by 2 and charge is reduced by 2 

(b) mass is reduced by 4 and charge is reduced by 6 

(c) mass is reduced by 2 and charge is reduced by 4 

(d) mass is reduced by 4 and atomic no. is reduced by 2.

Answer 1

The correct option is (d) mass is reduced by 4 and atomic no. is reduced by 2.

Explanation:

 When one α-particle is emitted, the mass (A) is reduced by 4 and atomic no. (Z) is reduced by 2. Therefore for new nucleus, mass no. is (A - 4) and atomic no. is (Z - 2).