Question

Assertion In $\alpha$-decay atomic number of daughter nucleus reduces by $2$ units from the parent nucleus.
Reason An $\alpha$-particle carries four units of mass.

• A. Both assertion and reason are true and reason is the correct explanation of assertion
• B. Both assertion and reason are true but reason is not the correct explanation of assertion
• C. Assertion is true but reason is false.
• D. Both assertion and reason are false.

Answer 1

Answer: (A)

We know that $\alpha$-particle carries two units of positive charge and four units of mass. In $\alpha$-decays, charge number of parent nucleus decreases by $2$ units. Also mass number reduces by four units.