Have you ever seen a bottle of it? If so, was the bubble of air at the bottom or the top? There's your answer. (No, it does not float in air. Very small droplets of it can be temporarily suspended in air, but it will eventually settle out.)
Air is a mixture of different gases but the most notable of these are Nitrogen, Oxygen and Carbon Dioxide.
As you heat any matter you increase the kinetic energy the particles of that matter have....
Oil and water will not mix as water is a polar substance and oil is nonpolar. Polar substances will only dissolve other polar substances or ionic substances, but not nonpolar substances. Thus, they...
Hot air rises and the fire in the hot air balloon wants to go up and float in the air and since it's can't escape the balloon the fire just brings the balloon with it to float in the air