Pentane (C₅H₁₂) and hexane (C₆H₁₄) form an ideal solution. At 25°C the vapor pressures of pentane and hexane are 511 and 150. torr, respectively. A solution is prepared by mixing 25 mL pentane (density, 0.63 g/mL) with 45 mL hexane (density, 0.66 g/mL).  

a. What is the vapor pressure of the resulting solution? 

b. What is the composition by mole fraction of pentane in the vapor that is in equilibrium with this solution?