What part of the atom is involved in chemical reactions?

Chemical reactions happen when two or more atoms go together to form molecules or when Atoms brake

The correct answer is b

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).