Ethan is observing chemical and physical properties of a substance. he heats a substance and observes that the substance turns from a brown solid to a black powder. he refers to several chemistry journals that claim this represents a chemical reaction. from his observation and research, he concludes that the substance goes through a chemical change when heated. how can ethan best defend his conclusion?
a by demonstrating that the substance will eventually melt if the temperature continues to increase
b by verifying that the substance is now made up of different molecules than before it was heated
c by verifying that the substance is made up of only one type of element
d by demonstrating that the substance is less dense after it is heated