1. How do you know when something is gas?

2. What is gas made of? [I think it's molecules and atoms?]

3. How do you know when something is matter? [I believe that when something has a mass and volume..its matter. Is that correct?

4. Is gas matter? [This question got me confused because we were taught that gas is a form of matter, but it has no definite shape or volume so why is it matter?

5. Does air take up space? How do you know?

6. Does air always take up the same amount of space? [I think it's no but I don't know how to explain it.]

These are the questions from my worksheets that I mostly have troubles with and I need to be cleared up on it please. Thank you.