Question

seans bike begins to rust in the winter. what tells sean that a chemical change is happening?
the metal fender is bent
the paint is scratched
the metal is beginning to rust
the bicycle was outside all winter

Explanation:

A chemical change involves the formation of new substances. Rusting of metal is a chemical reaction where iron reacts with oxygen and moisture to form iron oxide (rust). The other options like a bent fender (physical deformation), scratched paint (surface damage - physical), and the bike being outside (just a condition) are not chemical changes.

Answer:

The metal is beginning to rust.