According to the law of conservation of matter, the number of is not changed by a chemical reaction.

Answer ;

atoms

Explanation ;

The law of conservation of matter states that atoms cannot be created or destroyed by chemical reactions. Therefore, the number of atoms is not changed by a chemical reaction. However, the way the atoms are combined is changed, so the number of bonds, molecules, and products can all change.

water is used to store them because it would keep the radiation from getting out in the open and causing harm to the workers