How can you tell if something is a mixture?

Decide whether a substance is chemically pure. If it is pure, the substance is either an element or a compound. If a substance can be separated into its elements, it is a compound. If a substance is not chemically pure, it is either a heterogeneous mixture or a homogeneous mixture.

mark brainliest   :)

so easy. just google the electromagnetic waves and it’ll pop up.

i think the answer is a, hope this : )