Question

when you observe a chemical property, the substance...
goes through a phase change.
glows.
remains the same.
changes to a new substance.

Explanation:

Chemical properties describe how a substance reacts with other substances to form new substances. When observing a chemical property, a chemical reaction occurs, and the original substance changes into a new substance. For example, when iron rusts (a chemical property - reactivity with oxygen), it forms iron oxide (a new substance). Phase change (like melting ice - physical change) and glowing (could be physical like incandescence) don't involve forming new substances. A substance remaining the same would be a physical property observation.

Answer:

changes to a new substance.