which observation most likely indicates that only a chemical change has taken place?

Question

A. The change cannot be reversed
B. States of matter changes
C. A reaction occurs
D. The shape changes

Answer 1

C. A reaction occurs

A reaction typically indicates that a chemical change has taken place, as it often involves the breaking and forming of chemical bonds, resulting in the formation of new substances. In contrast, physical changes might involve changes in state or shape but do not alter the chemical composition of the material.