In an observation, a-particles, P-particles and y-rays have same energies. Their penetrating power in a given medium in increasing order will be

The penetrating power of ionizing radiation is inversely proportional to its mass and charge. Alpha particles (α) are the heaviest and most highly charged, consisting of two protons and two neutrons; they are easily stopped by a sheet of paper or human skin [2]. Beta particles (β) are much smaller and faster electrons, allowing them to penetrate skin but they are typically stopped by thin layers of aluminum or glass [1]. Gamma rays (γ) are weightless photons of pure energy with no charge, giving them the highest penetrating power [2]. They can pass through the human body and require thick lead or concrete to be obstructed [1]. Therefore, when these radiations have the same energy, the increasing order of their penetrating power is alpha (least), followed by beta, and then gamma (most) [1].

Sources

1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > 5.9.3. Tlpes of radiation particles > p. 82
2. [2] https://www.epa.gov/radiation/radiation-basics