Here's why:
* Air is made of matter: Air is composed of gases like nitrogen, oxygen, and others. Matter has mass.
* Mass is a fundamental property: Mass is a fundamental property of matter. It's a measure of how much "stuff" an object contains.
* Weight vs. Mass: While weight is a measure of the force of gravity on an object's mass, mass itself is a constant property.
* Balloon Experiment: If you inflate a balloon and then let go, it will fall to the ground due to its mass.
Therefore, air inside a balloon has a measurable mass, just like any other matter.
