Which quantity of o2 contains exactly 3.01 x 10^23 atoms? and you! not looking for answers, i am really stuck on this one

If 1.63 times 10 negative 4 of helium dissolves in 100.0g of water, what is the concentration in parts per million

Aradio signal from a gps satellite take only about 0.067 seconds to reach a gps reciever. if the speed of light is about 300,000km/s, then approximately how far away is the reciever from from the satellite?

Clyde and marilyn are riding a roller coaster. during which section(s) of the track is their potential energy converted to kinetic energy? a. from point b to point c only b. from point b to point d only c. from point a to point b only d. from point a to point b and from point c to point d