A Gas Mixture Has Partial Pressures of 120 Torr N₂

A gas mixture has partial pressures of 120 torr N₂, 350 torr Ar, and 480 torr SF₆. What is the mole fraction of sulfur hexafluoride in the mixture?

A) 0.13
B) 0.37
C) 0.45
D) 0.51
E) 0.55