You are building a shelf at home. As you sand the wood dust floats into the air. The air and dust from sanding create which of the following.

a. a solution

b. a pure substance

c. a colloid

d. a suspension

A colloid and a suspension are the same thing so it rules out c and d because the dust is heavier than air causing it to float down but not float constantly. a pure substance is one solid substance. so its be A. a solution. a solution is a homogenous mixture of 2 or more substances because it wouldn't only compose of wood dust because of the air oxygen and carbon dioxide keeping it from falling faster.

Solution, colloids and suspension are different kind of mixtures.

Air and dust are not solutions, because the dust can be observed (using light).

There is a doubt about whether air and dust form a colloid or a suspension.

Colloids do not separate, while suspension's components do separate. If the dust is small enough it will remain on the air long enough to be considered a colloid for all efects.

Then, the most acceptable opinion is that the mixture of air and dust is a colloid.

So, option c. a colloid.