Step-by-step explanation:
Alpha particles are less penetrating than a beta or gamma particle. Alpha particles are doubly charged helium nuclei. It consists of two neutrons and two protons.
The penetration of any ray is given by the following relation :
T = e^-u * L
Where
T is the transmittance of any material
u is the coefficient of penetration
L is the length of penetration
The mass and charge of alpha particle is more as compared to beta and gamma particles. They can produce ions easily. So, they penetrate more when compared to beta and gamma rays.