The charge on alpha particle is

 positive

Explanation:

An alpha particle is a type of ionizing radiation consisting of two protons and two neutrons bound together, identical to the nucleus of a helium-4 atom. Due to the presence of two protons, an alpha particle carries a positive charge of +2e, where e represents the elementary charge (approximately 1.6 × 10⁻¹⁹ coulombs).

Therefore, the total charge of an alpha particle is 2 × 1.6 × 10⁻¹⁹ C, which equals 3.2 × 10⁻¹⁹ C.

In terms of mass, an alpha particle has a mass of approximately 6.644 × 10⁻²⁷ kilograms, which is equivalent to four atomic mass units (amu), as it comprises two protons and two neutrons.

Alpha particles are emitted during the alpha decay of heavy radioactive nuclei such as uranium-238 and radium-226. This process reduces the mass number of the original nucleus by four and the atomic number by two, resulting in the formation of a new element. For example, when uranium-238 undergoes alpha decay, it transforms into thorium-234.

Due to their relatively large mass and charge, alpha particles have low penetration power and can be stopped by a sheet of paper or even the outer layer of human skin. However, if alpha-emitting materials are ingested or inhaled, they can pose serious health risks due to their high ionizing capability.

In summary, the charge of an alpha particle is +2e, corresponding to a total charge of 3.2 × 10⁻¹⁹ coulombs, and it has a mass of approximately 6.644 × 10⁻²⁷ kilograms.