What's the average atomic mass of bromine and state which isotope is more abundant?

The answer would be Br-79 because it is 50.69% abundant.

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.