Okay, so what you first do with this type of question is think about what a chemical change is. A chemical change is a change that can not be reversed. A physical change is something that can be reversed or done using temperature. e.x. Water freezing into ice is a physical change, where as combining vinegar and baking soda together releases a gas, which is chemical, or iron rusting in the presence of oxygen. Which one of these equations has one chemical molecule set that produces a different set?
