Pure substances can be elements or compounds. An element is a form of matter that cannot be broken down by chemical reactions into simpler substances. A compound is a substance composed of two or more different types of elements ,chemically combined in a fixed ratio. 2.(a) Elements and compounds are called as pure substances because it is made up of _________________ *
a.same kind of atoms or molecules
b. different kinds of atoms or molecules
c.heterogeneous mixtures
d.solutions