Question

air can be considered a mixture. which statement helps describe air? a air contains a fixed ratio of atoms. b the components of air separate into visible layers. c the components of air can be separated by chemical means. d the exact mixture of components varies from point to point.

Explanation:

A mixture has components that are not in a fixed ratio (so A is wrong). Air components don't separate into visible layers (so B is wrong). Mixture components are separated by physical means, not chemical (so C is wrong). In a mixture like air, the exact composition can vary from place to place.

Answer:

D. The exact mixture of components varies from point to point.