Which has a larger impact on change in atomic size: moving down one period or moving across a family

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.

Which term refers to a property that depends only on the amount of a substance? ©@

What is the formula that this ionic compounds could form sr2+p3-o2-