Question

39. When a nucleus undergoes radioactive decay, its new mass number is
1) always less than its original mass number
2) always more than its original mass number
3) never more than its original mass number
4) never less than its original mass number​

Answer 1

Answer:

1) always less than its original mass number

Explanation:

When a substance undergoes radioactive decay it divides to form a smaller atom which is higher in the periodic table, i.e, Has lesser mass number.

Therefore, When a nucleus undergoes radioactive decay, its new mass number is  always less than its original mass number.