Examine the equation. 23490th→23088ra+42he what kind of barrier would you need to block the radioactive particles from this reaction? a. a piece of paper b. a sheet of aluminum foil c. a two-inch block of lead d. a solid concrete block

A. A piece of paper

Explanation:

The equation describes an alpha-decay, in which an alpha particle is produced.

An alpha particle is a nucleus of helium, consisting of 2 protons and 2 neutrons (in the formula, it corresponds to 42He, where 4 is the mass number and 2 is the atomic number).

Among all types of radiation, alpha-radiation is the less penetrating one. In fact, since the alpha particle has a great mass and charge, it easily ionises the atoms of the mediums where it is passing through, releasing its energy at a very fast rate. For this reason, alpha particles usually lose all their energy in a very few mm of material, therefore they can be easily stopped even by a piece of paper.