What material effectively blocks alpha particulates?

Alpha particles are relatively heavy and carry a positive charge, which significantly limits their range and penetration ability. They are unable to penetrate through even the simplest materials. Among the options provided, paper is particularly effective at blocking alpha particles due to its ability to absorb the relatively low energy that alpha radiation possesses.

When alpha particles collide with the fibers in paper, they lose their energy quickly and are halted, making paper a very practical and accessible material for shielding against this type of radiation. It's important to note that while plastic, metal, and glass can also offer some degree of protection from alpha particles, they are usually more relevant in shielding against beta or gamma radiation where penetration is a greater concern. Thus, paper is the most appropriate and effective choice when dealing specifically with alpha radiation.