9. A block of dry ice (solid CO2, density =1.56g/mL ) of dimensions 25.0cm25.0cm25.0cm is left to sublime (i.e., to pass from the solid phase to the gas phase) in a closed chamber of dimensions 4.00m 5.00m3.00m. Once the sublimation is complete, what is the partial pressure of carbon dioxide in the chamber at 25C?(R=0.08206Latm/Kmol,1atm=760mmHg) 20. Freon-12, CF2Cl2, which has been widely used in air conditioning systems, is considered a threat to the ozone layer in the stratosphere. Calculate the root-mean-square velocity of Freon-12 molecules in the lower stratosphere where the temperature is 65C