Question

A nuclide has mass number $\left(A\right)$ and atomic number $\left(Z\right)$. During a radioactive process if
1. both $A$ and $Z$ decrease, the process is called $\alpha$-decay.
2. $A$ remains unchanged and $Z$ decreases by one, the process is called ${\beta }^{+}$ or positron decay or $K$-electron capture.
3. both $A$ and $Z$ remain unchanged, the process is called $\gamma$-decay.
4. both $A$ and $Z$ increase, the process is called nuclear isomerism.
The correct answer is:

• A. 1, 2 and 3
• B. 2, 3 and 4
• C. 1, 3 and 4
• D. 1, 2 and 4

Answer 1

The correct option is A 1, 2 and 3

Alpha decay: Here the mass number is decreased by 4 and the atomic number is decreased by 2. Hence option 1 is correct.

Beta-decay: Nucleus emits an electron and antineutrino. So option 2 is also correct.

Gamma decay: Emission of only gamma rays and no change in the mass number or atomic number. Hence option 3 is also correct.

Nuclear Isomerism occurs when atoms have the same mass number and atomic number but energy levels are different. Hence option 4 is incorrect.

So the correct option is A.