How to know if a guy is really into you?

In a sample of oxygen gas at room temperature, the average kinetic energy of all the balls stays constant. which postulate of kinetic molecular theory best explains how this is possible? a. attractive forces between gas particles are negligible because the particles of an ideal gas are moving so quickly. b. collisions between gas particles are elastic; there is no net gain or loss of kinetic energy. c. gases consist of a large number of small particles, with a lot of space between the particles. d. gas particles are in constant, random motion, and higher kinetic energy means faster movement.

Iknow the answer is a but i don't know why

Read these sentences from the text. near the equator, the tropics receive the most rain on a consistent basis. as a result, the fresh water falling into the ocean decrease the salinity of the surface water in that region. [. .] . . as the salt content of sea water increases, so does its density. what can you infer about how rain affects the density of surface water near the equator?