Question

which answer below correctly identifies the type of change and the explanation for the mixture of calcium carbonate and hydrochloric acid?
physical change because even though gas formation was observed, the calcium carbonate retained its original properties
physical change because even though a particle size change was observed, the calcium carbonate retained its original properties
chemical change because gas formation was observed, which indicated that the calcium carbonate was transformed into a different substance
chemical change because a particle size change was observed, which indicated that the calcium carbonate was transformed into a different substance

Explanation:

In a chemical change, new substances are formed. Gas formation during the reaction of calcium carbonate and hydrochloric - acid shows a chemical reaction has occurred and calcium carbonate has changed into other substances. Physical changes do not result in new substances, so the presence of gas formation rules out physical - change options.

Answer:

C. chemical change because gas formation was observed, which indicated that the calcium carbonate was transformed into a different substance