Here's how to calculate the freezing point of the solution:

1. Understand the Concept

* Freezing Point Depression: When a non-volatile solute (like benzene) is dissolved in a solvent (like chloroform), the freezing point of the solution decreases compared to the pure solvent.

* Freezing Point Depression Equation: ΔT_f = K_f * m

* ΔT_f = Change in freezing point

* K_f = Cryoscopic constant of the solvent (for chloroform, K_f = 4.68 °C/m)

* m = Molality of the solution (moles of solute per kg of solvent)

2. Calculate Molality (m)

* Moles of Benzene:

* Molar mass of benzene (C₆H₆) = 78.11 g/mol

* Moles of benzene = (2.50 g) / (78.11 g/mol) = 0.0320 mol

* Mass of Chloroform in kg:

* 120 g = 0.120 kg

* Molality:

* m = (0.0320 mol) / (0.120 kg) = 0.267 mol/kg

3. Calculate the Change in Freezing Point (ΔT_f)

* ΔT_f = (4.68 °C/m) * (0.267 mol/kg) = 1.25 °C

4. Determine the Freezing Point of the Solution

* Freezing Point of Pure Chloroform: -63.5 °C

* Freezing Point of the Solution: -63.5 °C - 1.25 °C = -64.75 °C

Therefore, the freezing point of the solution containing 2.50 g benzene in 120 g chloroform is -64.75 °C.