The least penetrating power ray is A)X-Ray B)a-Ray C)b-Ray D)g-Ray
Option B) Since alpha particles are high in ionizing power, it is difficult for them to penetrate matter thoroughly. This is because alpha particles are likely to ionize the first thing they come into contact with; thus, they hold a small range of penetrating power. Beta rays have intermediate; while, Gamma Rays and X Rays have maximum penetrating power.
Opt. B
