Astudent fills a paper cup with water and puts it in a freezer over night. when she takes the cup out the next day, she notices that the sides of the cup are pushed out. why did this happen. explain?

When the chemicals iron sulfide (fes) and hydrochloric acid (hcl) are combined, bubbles appear from the mixture. 1. does the appearance of bubbles indicate a physical or chemical change? 2. why do the bubbles indicate this change? 3. what property is this?