Which substance can not be broken down by a chemical change?18 Which equation represents a physical

NYC Chemistry Regents Exam Jan 2023

Which substance can not be broken down by a chemical change? (1) ammonia

(2) ethanol (3) krypton

(4) water

Solution: Elements can not be broken down by a chemical change. Krypton is an element (you can find it on the Periodic Table) and the rest of the answer choices are compounds.