Q198 / 200 · MHT CET - Medical 2026 (24 April Shift 2) · Physics
When a nucleus in an atom undergoes a radioactive decay, the atomic number and/or mass number of the atom
- Ado not change for any type of radioactivity.
- Correct answerBchange for $\alpha$ and $\beta$ radiations but not for $\gamma$ radiation.
- Cchange for $\alpha$ radiation but not for others.
- Dchange for $\beta$ radiation but not for others.
Solution
In $\alpha$ decay, the atomic number decreases by $2$ and the mass number decreases by $4$.
In $\beta$ decay, the atomic number changes by $1$ (increases in $\beta^{-}$ and decreases in $\beta^{+}$) while the mass number remains unchanged.
In $\gamma$ decay, neither the atomic number nor the mass number changes, as it only involves a transition between nuclear energy levels.
Thus, the atomic number and/or mass number change for $\alpha$ and $\beta$ radiations but not for $\gamma$ radiation.
Answer: change for $\alpha$ and $\beta$ radiations but not for $\gamma$ radiation.
In $\beta$ decay, the atomic number changes by $1$ (increases in $\beta^{-}$ and decreases in $\beta^{+}$) while the mass number remains unchanged.
In $\gamma$ decay, neither the atomic number nor the mass number changes, as it only involves a transition between nuclear energy levels.
Thus, the atomic number and/or mass number change for $\alpha$ and $\beta$ radiations but not for $\gamma$ radiation.
Answer: change for $\alpha$ and $\beta$ radiations but not for $\gamma$ radiation.
Hence, the correct answer is option: 'B'.