Real gases behave most nearly like ideal gases at 1. low temperatures and low pressures. 2. high pressures and low molar masses. 3. high temperatures and high pressures. 4. low temperatures and high pressures. 5. high temperatures and low pressures.

high temperatures and low pressures

Explanation:

At high temperature and low pressure, individual gas molecules are relatively free from intermolecular interaction and move about freely with maximum kinetic energy. Recall that ideal gases are believed not to possess intermolecular forces of attraction hence the molecules are free and move at very high velocity and and maximum kinetic energy. Real gases at low temperature and high pressure associate considerably via van der Waals forces.

i'm assuming that it's c.) red bank..

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.