At 25 °C a 0.50 g sample of polyisobutylene (a polymer used in synthetic rubber) in 100.0 mL of benzene solution has an osmotic pressure that supports a 5.1 mm column of solution (d = 0.88 g/mL). What is the molar mass of the polyisobutylene? (For Hg, d = 13.6 g/mL.)