Which have more molecules ? 20 g of ammonia or 30 g of oxygen gas?

The tilt of the earth's axis of rotation is responsible for the a) ocean's tides. b) size of the moon. c) brightness of stars. d) earth’s seasons.

Which of the following would have less momentum than a 52 kg cheetah running at 10 m/s?

How many mmols of tris-hcl are there in 100 ml of a 100 mm tris-hcl buffer solution at ph 8.1? note that the 100 mm refers to the sum of tris and tris-hcl concentrations?