dropping an Alka-Seltzer tablet into a glass of water b. bleaching a stain c. burning a match d. rusting of an iron nail

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.

The answer is d.potassium