The pressure of a sample of gas of constant volume is 2.0 atm at 30.ºC. What is the pressure of this sample at 20.ºC?

Can someone me with questions 15 to 17 plz.

In which environment would primary succession occur? a forest with a few remaining trees after a recent wildfire an area of exposed rock after a glacier melts away beach that is exposed to the air at low tide an abandoned baseball field in a small town

At 20°c, a sample of h2o liquid and a sample of co2 gas each have the same average kinetic energy. why is one a liquid and the other a gas at this temperature?