Question

Why is a homogeneous mixture not considered a pure substance?

A: A pure substance can be separated by chemical means, while a mixture can be separated by physical means.
B: Only heterogeneous mixtures are pure substances.
C: A mixture contains one substance, while a pure substance contains more than one.
D: A pure substance can be separated by physical means, while a mixture can be separated by chemical means.

Answer 1

The answer is "A. a pure substance can be separated by chemical means, while a mixture can be separated by physical means". A pure substance only has one type of substance, whereas a mixture has more than one. A pure substance therefore, can only be separated chemically, because it is not two things mixed together, whereas a mixture can be separated physically because there are multiple substances.