He adds a few drops of hydrogencarbonate indicator to the jar and the colour of the indicator does not
change. But not oxygen.

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.

Idk the answer imthink snail cant mate they dont lol

As cooking food that has to go in the oven