Asap! i promise i will mark the first fastest, quickest answer brainliest! and you will get 10 i am being timed with 1 hour and 3 minutes left but i still have to answer 50 questions! which of the following is a clue that a chemical change has occurred? a. iron changes color when heated b. gas bubbles form in boiling water c. balls of wax form when melted wax is poured into ice water d. a gas forms when vinegar and baking soda are mixed tysm! ☺♥