Question

In a radioactive process, the atomic number of the element may or may not changed. If the parent atom undergoes successive radioactive decays : alpha, beta and gamma. How many atomic number of daughter atom is less than parent atom?

• A. 1
• B. 2
• C. 4
• D. 5
• E. 7

Answer 1

The correct option is A 1

In alpha decay, the atomic number of parent nucleus decreases by $2$.

In beta decay, the atomic number of parent nucleus increases by $1$.

Whereas the atomic number of the parent nucleus remains the same in gama decay.

Reaction : ${}_Z^{A}X$ $\to$ ${}_{Z-2}^{A-4}Y$ $\to$ ${}_{Z-1}^{A-4}{W}^{\ast }$ $\to$ ${}_{Z-1}^{A-4}W$

Thus overall the atomic number of daughter is less than parent atom by $1$.