Acc. to Law of Conservation of Mass
Mass of reactants=Mass of Products
Let mass of Oxygen be x.
So,
50.6+x=452
x=452-50.6
=401.4 g
How it looks. basically the thing that tells you how it change. for example if an ice cube was melted (heat), it only changed physically not chemically as the h20 molecules are still there. however lets say you burn woos— you cant get that would back. its ash now and it has changed chemically.
