HELP WITH PHYSICAL VS. CHEMICAL CHANGES?

Question

which one is physical and which one is chemical? and how do you know the difference? please help!!

corrosion of aluminum metal

melting of ice

pulverizing an aspirin

digesting a candy bar

explosion of nitroglycerin

Answer 1

Physical changes occur when the substance which although may look different is the same substance before and after the reaction. Chemical changes occur when the substances present in the beginning are not present at the end and new products are formed.

corrosion of aluminum metal - CHEMICAL

melting of ice - PHYSICAL

pulverizing an aspirin - PHYSICAL

digesting a candy bar - CHEMICAL

explosion of nitroglycerin - CHEMICAL