Heat question on science?

Question

what happens when air is heated?

Answer 1

Particles will vibrate faster and will collide with each other creating random motion.

Answer 2

Molecules will be moved farther to each other.

Answer 3

denser

Answer 4

The molecules expand and spread out.  They speed up too.  That's why hot farts can spread so fast across a room.  As to whether or not the molecules might come apart, hmmmm, I don't know.  I suppose with enough heat they could.

Answer 5

Heating air is, literally, "transferring energy to air".  As the temperature of the air increases, the air molecules become more "excited", their motion is increased, and the average distance separating the molecules increases (effectively decreasing the density/increasing the volume).  This is why hot air balloons float- it takes less air to fill the balloon because the mollecules are further apart (which, by definition, means the density is decreased) and because the density is lower inside the balloon when compared to the air outside the balloon, it floats.  This is also how your car's eninge works.  When a spark plug fires and ignites the fuel misture in the cylinders, the air in the cylinders is heated causing the air to expand in the enclosed space.  This causes an increase in pressure which forces the pistons to move.

I should note, if you heat air enough, it will begin to ionize (the electrons will begin to separate from the atoms).  This state of matter is called "plasma".  Just as solids turn to liquids when sufficiently heated and liquids turn to gasses when sufficiently heated, gases will eventully turn to plasma which has its own unique set of properties and behaviors.