International General Certificate of Secondary Education (IGCSE) Physics Practice Exam

A beta particle is indeed more penetrating than an alpha particle due to its smaller mass and charge. Alpha particles consist of two protons and two neutrons, making them relatively heavy and positively charged. As a result, they interact strongly with matter and have a limited range in materials; they can be stopped by just a few centimeters of air or a sheet of paper.

In contrast, beta particles are much lighter, being electrons or positrons, and possess a negative or positive charge, respectively. Their smaller size allows them to penetrate further into materials. They can pass through paper and a few millimeters of plastic or even soft tissues, which makes them generally more penetrating than alpha particles.

While the energy of the particles can affect their penetrating ability, generally, the characteristic differences in mass and charge lead to the conclusion that beta particles are more penetrating than alpha particles under standard conditions.