Question

A nuclide $A$ undergoes $\alpha$ decay and another nuclide $B$ undergoes ${\beta }^{-}$decay.

• A. All the $\alpha$ particles emitted by $A$ will have almost the same speed.
• B. All the $\alpha$ particles emitted by $A$ may have widely different speeds.
• C. All the $\beta$ particles emitted by $B$ will have almost the same speed.
• D. All the $\beta$ particles emitted by $B$ may have widely different speeds.

Answer 1

Answer: (A), (D)

All the $\beta$ particles emitted by $B$ may have widely different speeds.

In $\alpha$ decay, only $\alpha$ particle is emitted, so the entire energy is carried away by the alpha particle as its Kinetic energy.

Therefore, all $\alpha$ particles have same speed.

In ${\beta }^{-}$ decay, $\beta$ particle and anti-neutrino are emitted, so the energy is shared between the $\beta$-particle and anti-neutrino.

Therefore, the speed of $\beta$ particle will vary depending on the energy of the anti-neutrino.

Hence, options $\left(A\right)$ and $\left(D\right)$ are correct.