Why are the levels of the mercury in the two arms of the U-tube the same when there is no gas in the flask?

When molecules of water vapor in the air come in contact with a cold can of soft drink , they lose energy ,slow down, and form a liquid due to decrease in ?

Endeleev saw trends in the physical and chemical properties of elements when he organized them by

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.