Electrons make up most of the atom's mass. True or false ?

Why does a plastic bottle that is sealed at a high altitude change it’s shape when taken to lower altitude

In a heat engine of 1000 j of heat enters the system and the piston does 500 j of work what is the final internal energy of the system if the inital energy was 2000 j we have to do all of these down here 1)write the equation 2)list out your know variables 3)plug the numbers into the equations 4)solve 5)write your solution statemtn that includes inital energuy and final energuy added

Once similarity and one difference between a mixture of elements and a mixture of compounds