Which particle is known to be an electron and can be shielded by plastic?

Beta particles are indeed the correct choice because they are high-energy, high-speed electrons or positrons that are emitted during the radioactive decay of certain types of nuclei. Due to their smaller mass and charge, beta particles can be shielded effectively by materials like plastic, which can absorb and stop them from penetrating further.

Plastic works well as a shielding material for beta particles because it provides the necessary thickness and molecular structure to capture the charged particles through interactions with its electrons. This contrasts sharply with alpha particles, which, while also charged, are larger and can be stopped by a sheet of paper or even the outer layer of human skin. Gamma rays, on the other hand, are not charged and require denser materials like lead or concrete for shielding, as they can penetrate deeply into most materials. Neutrons, being neutral particles, are better shielded by materials rich in hydrogen, such as water or polyethylene. Understanding the properties of these various particles and the types of materials that can shield them is crucial in radiation safety practices.