How many liters would 2.50 x 10^27 molecules of sulfur trioxide gas occupy?

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same

If i initially have a gas at a pressure of 12 atm, a volume of 23 liters, and a temperature of 200 k, and then i raise the pressure to 14 atm and increase the temperature to 300 k, what is the new volume of the gas?

A50.0g sample of liquid water at 0.0 c ends up as ice at -20.0 c. how much energy is involved in this change?