Chlorofluorocarbons such as CCl₃F and CCl₂F₂ have been linked to ozone depletion in Antarctica. As of 1994, these gases were found in quantities of 261 and 509 parts per trillion (10¹²) by volume (World Resources Institute, World resources 1996–97). Compute the molar concentration of these gases under conditions typical of

(a) The mid-latitude troposphere (10°C and 1.0 atm) and

(b) The Antarctic stratosphere (200 K and 0.050 atm).