The ionising power of `alpha-`particle is less compared to `alpha-`particles but their penetrating power is more.
The mass of `beta-`particle is less than the mass of `alpha`-particle.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If the assertion and reason both are false

Answer

B

Explanation

`beta`- particles, being emitted with very high speed compared to `alpha`- particles, pass for very little time near the atoms of the medium. So, the probability of the atoms being ionised is comparatively less. But due to this reason, their loss of energy is very slow, and they can penetrate the medium through a sufficient depth.