On mixing, heptane and octane form an ideal solution. At 373 K, the vapour pressure of the two

liquid components (heptane and octane) are 105 kPa and 45 kPa respectively. Vapour pressure

of the solution obtained by mixing 25g of heptane and 35g of octane will be (molar mass of heptane

= 1 00g mol^{- 1} and of octane = 114g mol^{- 1})

(1) 72.0 kPa (2) 36.1 kPa (3) 96.2 kPa (4) 144.5 kPa