Multiple choice general knowledge science & technology A solution composed completely of gases is... petroleum soda air Kool-Aid Reveal answer Fill a bubble to check yourself C Correct answer Explanation Air is a homogeneous mixture of gases (nitrogen, oxygen, argon, CO2, etc.), making it a solution composed entirely of gases. Petroleum is liquid hydrocarbon mixture, soda is liquid with dissolved gas, and Kool-Aid is solid dissolved in liquid.