You tested for the presence of the alkene functional group using KMnO4. A positive test was indicated by the appearance of a brown MnO2 precipitate. What happens to the alkene when the permanganate is reduced to MnO2

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.

Sorry i dont understand the question can you rephase it?

Your question is not clear but if you can explain yourself i would be glad to .  just trying to : ))