Question

physical vs. chemical change quick check
which of the following is a reliable way to observe that a chemical change has occurred when two substances come in contact with one another? (1 point)
conduct a test to determine the chemical makeup of the molecules
monitor for the release of a gas
observe a color change
test for the release of heat

Explanation:

A chemical change involves a change in the chemical makeup of substances. While gas release, color - change, and heat release can be signs of chemical change, they are not always conclusive. Conducting a test to determine the chemical makeup of the molecules is the most reliable way as it directly checks for the formation of new substances, which is the essence of a chemical change.

Answer:

conduct a test to determine the chemical makeup of the molecules