A sample of elemental carbon is 20% carbon-13 and 80% carbon-14. What is the average mass of carbon in the sample?

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.

Answerhave membrane-bound organelles;

The bergeron process.