If traveling at equal velocities, which object would have the most momentum? a. a featherb. a baseballc. a hockey puckd. a bowling ball

What does a numerical subscript following an element in a chemical formula mean?

Can someone me out on this question for my national 5 chemistry homework

How does a sample of helium at 15 degree celsius compare to a sample of helium at 215 k? a) the helium at 15 degrees celsius has a higher average kinetic energy that the sample at 215 k. b) the helium at 15 degrees celsius has lower nuclear energy that the sample at 215 k. c) the helium at 15 degrees celsius has slower- moving atoms that the sample at 215 k. d) the helium at 15 degrees celsius has smaller atoms than the sample at 215 k.