Question

A radioactive nucleus will not emit:

• A. alpha and beta rays simultaneously
• B. beta and gamma rays simultaneously
• C. gamma and alpha rays
• D. gamma rays only

Answer 1

Answer: (D)

$\alpha$ rays are nucleus of He atom, $\beta$ rays are electrons and $\gamma$ rays are energy particles.
A radioactive substance first emits $\alpha$ and $\beta$ particles.
Now it becomes excited. In order to come down to ground state, it now emits $\gamma$ particle.
$\therefore$ Radioactive substance cannot emit $\gamma$ rays only. They will always be emitted after $\alpha$ or $\beta$ emission.