Question

which of these is not an example of matter?
the sound of a bird chirping
the feathers on a bird
the air under a birds wings
the sticks in a birds nest

Explanation:

Matter is anything that has mass and takes up space. Feathers, air, and sticks all have mass and occupy space. Sound, however, is a form of energy (mechanical energy in the form of vibrations) and does not have mass or occupy space in the way matter does.

Answer:

The sound of a bird chirping