A 500-L tank contains 15 mg/L of trichloroethylene (TCE; C2HCl3) dissolved in water. What is the TCE concentration in ppm if the tank is held at (a) 4 degrees C and (b) 35 degrees C? (c) What is the TCE concentration in ppm if the tank is filled with hexane instead of water? Consult Appendix A for the temperature dependence of the density of water, while the density of TCE is 1.464 kg/L and density of hexane is 0.6603 kg/L.