Gases have some interesting behaviors when it comes to how their volume changes with pressure.

1. Compressibility: Gases can be squished a lot! When you apply a lot of pressure, the volume of a gas can shrink by up to 99%. For instance, at room temperature, one mole of gas takes up 22.4 liters if the pressure is normal (1 atm). But if you increase the pressure, the volume of that gas gets much smaller.

2. Ideal Gas Law: There’s a formula that helps explain how gases behave, which is:

   PV = nRT

   In this formula:

   • P stands for Pressure,
   • V stands for Volume,
   • n is the Number of moles (this just counts how much gas there is),
   • R is a constant for ideal gases (which is 0.0821 when using liters and atm),
   • T is Temperature measured in Kelvin.

3. General Behavior: One important rule about gases is called Boyle's Law. It says that if the temperature stays the same, the volume of a gas will change in the opposite way to the pressure. So, if you double the pressure, the volume will be cut in half.

This means that gases are very flexible and change their size easily when pressure is applied!