Which answer below correctly identifies the type of change and the explanation when magnesium comes into contact with hydrochloric acid?

Magnesium reacts with hydrochloric acid to form new substances: magnesium chloride and hydrogen gas. The solid magnesium disappears and gas bubbles form, and the reaction can also cause a temperature change. These observations indicate a chemical change, so choice C is correct. Simply mixing two substances does not always produce a new substance, which makes D’s explanation incorrect.

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