On mixing, heptane and octane form an ideal solution. At $373\text{K}$, the vapour pressures of the two liquid components (heptane and octane) are $105\text{kPa}$ and $45\text{kPa}$ respectively. Vapour pressure of the solution obtained by mixing $25.0\text{g}$ of heptane and $35\text{g}$ of octane will be (molar mass of heptane $=100{\text{g mol}}^{-1}$ and of octane $=114{\text{g mol}}^{-1}$):

1. A
   $72.0\text{kPa}$
2. B
   $36.1\text{kPa}$
3. C
   $96.2\text{kPa}$
4. D
   $144.5\text{kPa}$