Which of the following is NOT a variable property for a gas?

A. mass

B. density

C. volume

D. shape

Mass, air has that. Since what fills up a balloon? A gas

Shape, it has no definite shape. This one is accurate, it has no definite shape, it takes the shape of the object it's in.

Volume, does air take up space? If it does then yep. Balloon example/

Density, yes it does, because it's tightly wounded up.

D