Is calcium fluoride a pure substance, element, compound, or mixture?

The correct answer is compound.

Explanation:

A pure substance is defined as the substance which is formed by same or different type of atoms which are chemically combined in a fixed ratio by mass.

A compound is a substance which is formed by two or more different type of atoms when they chemically combine.

An element is defined as the substance which have only one type of atoms.

Mixture is defined as the solution which is made by the combination of two or more substances in which each substances retain their original chemical properties.

Calcium fluoride is made by the chemical combination of calcium and fluorine atoms. Thus, it is considered as a compound.

Hence, the correct answer is compound.

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.