Key constants and parameters: R=0.08206Latmmol1K1:R=8.314Pam3mol1K1:0C=273K:NAv=6.021023: Mass atmosphere =5.151021g : Average Mol. Wt. atmosphere =29.0gmol1 : 1Gt (Gigatonne) =11015g:1Mt (Megatonne) =1109kg=1Tg( Teragram )=11012g : 1m3=1000L=1106cm3:1L water =1kg. 1. HFC-125 (pentafluoroethane, M.Mass 120.0) is a refrigerant that has been in commercial production for about 10 years. It has a rate constant for reaction with HO radical of 2.51015cm3molec1s1. a) If the average concentration of HO radical in the atmosphere is 4.0105moleccm3, and assuming hydroxyl radical reaction is the dominant mechanism for removing HFC-125 from the atmosphere, what is the average lifetime of HFC-125 (in years)? (2 marks) b) The current rate of release of HFC-125 to the atmosphere is 57.5kt (kilotonnes) per year. Assuming this rate is maintained, what will be the eventual steady-state concentration of HFC-125 (in ppm)? (2