Which type of radiation can be easily blocked by paper?

Alpha radiation is made up of helium nuclei, which consist of two protons and two neutrons. Due to their relatively large mass and positive charge, alpha particles interact significantly with matter. When alpha radiation encounters materials, it loses energy quickly and is unable to penetrate even a few centimeters of air. In fact, a sheet of paper is sufficient to absorb alpha particles, effectively blocking them from passing through. This property makes alpha radiation much less hazardous outside the body, although it can be more dangerous if ingested or inhaled.

In contrast, beta radiation consists of electrons or positrons, which are lighter and can penetrate paper; gamma radiation is highly penetrating electromagnetic radiation that requires dense materials like lead or several centimeters of concrete for shielding. X-rays also fall into a similar category as gamma rays and are not effectively blocked by paper due to their penetrating power. Thus, alpha radiation is the type that can be easily blocked by paper.