Suppose you have a 100 of 0.1 potassium chloride to make it 0.2 M you need: A add 0.1 mole of potassium chloride B evaporate 50 mL of solution C evaporate 50 mL of water D add 100 ml of 0.1 potassium chloride

Aphysical change is one that you can put in and remove like a ham sandwich. the stuff you put in there can be changem its not permanet. a chemical change is on that can't be change thats permanet. like when you make a cake and bake it. you can't get those ingredients back.