Final answer:
A solution is a homogeneous mixture that appears clear and does not settle out or separate. If bubbles of gas are observed within the liquid, the mixture is not homogeneous and, thus, not a solution.
Step-by-step explanation:
A solution is a homogeneous mixture that appears clear and does not settle out or separate. Unlike suspensions or colloids, which contain larger particles that can settle or remain dispersed, a true solution contains dissolved particles that are very small, usually less than 1 nm in diameter. If bubbles of gas are observed within the liquid, the mixture is not homogeneous and, thus, not a solution.