On dissolving 0.5 g of non-volatile, non-ionic solute to 39 g of benzene, its vapour pressure decreases from 650 mm of Hg to 640 mm of Hg. The depression of freezing point of benzene (in K) upon addition of the solute is __________.
(Given data: Molar mass & molar freezing point depression is 78 g `mol^(-1) & 5.12 K kg mol^(-1)`]

Explanation

To solve the problem of finding the depression of the freezing point of benzene upon dissolving a non-volatile, non-ionic solute, we will follow these steps:

### Step 1: Understand the Given Data
- Mass of non-volatile solute (m_solute) = 0.5 g
- Mass of benzene (m_benzene) = 39 g
- Initial vapor pressure of benzene (P₀) = 650 mm Hg
- Vapor pressure of solution (P_s) = 640 mm Hg
- Molar mass of benzene (M_benzene) = 78 g/mol
...