On a sensitive balance, weigh an empty, flat, thin plastic bag. Then weigh the bag filled with air. Discuss whether or not the readings differ.
a) The readings will differ because the weight of the air adds to the weight of the bag.
b) The readings will not differ because air has negligible weight.
c) The readings will differ because the weight of the bag compresses the air inside.
d) The readings will not differ because the weight of the bag offsets the weight of the air.