Question

If uranium (mass number 238 and atomic number 92) emits an α -particle, the product has mass number and atomic number 

(a) 236 and 92

(b) 234 and 90

(c) 238 and 90

(d) 236 and 90

Answer 1

The correct option (b) 234 and 90

Explanation:

Emission of α-particle means mass is decreased by 4 units and charge by 2 units. Thus,

Thus, the mass number = 234 

atomic number = 90