How many moles of H2O will be produced if 6.8 mol of O2 reacts completely with CH4

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.

Ibelieve its because the stove is a cleaner burning fuel