The chemical and physical process that change things over time are called

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).

Iron reacts with oxygen in a chemical hand-warmer. how should this reaction be categorized? the correct answer is: a). as an exothermic process because it releases heat