If 500 mL of benzene is spilled in a sealed room (64m^3), and it completely evaporates, what mass of GAC filters (Cmax = 80 mg benzene/1 g GAC) will be required to reach the permissible exposure limit for benzene? (1 ppm (v/v) OSHA permissible exposure limit for benzene). GAC density = 0.602 g/mL