* Chemical Change: A chemical change involves the formation of new substances with different properties. Rusting is a chemical reaction between iron (in the wheel), oxygen (from the air), and water (from the environment). This reaction forms iron oxide, which is the reddish-brown substance we know as rust. Rust has different properties than iron, including color, texture, and strength.

* Physical Change: A physical change alters the form or appearance of a substance but does not change its chemical composition. Examples include melting ice, cutting paper, or boiling water.

In the case of a bike wheel:

* The iron in the wheel reacts with oxygen and water to form rust.

* This reaction is irreversible, meaning you can't easily change rust back into iron.

* The rust has a different chemical composition than the original iron.

Therefore, rusting is a chemical change because it results in the formation of a new substance (rust) with different properties than the original iron.