1. Calculate the moles of the compound:

* Use the ideal gas law: PV = nRT

* P = Pressure = 750 torr = 750/760 atm

* V = Volume = 256 mL = 0.256 L

* n = Number of moles (what we want to find)

* R = Ideal gas constant = 0.0821 L·atm/mol·K

* T = Temperature = 373 K

* Rearrange the equation to solve for n:

n = (PV)/(RT)

n = (750/760 atm * 0.256 L) / (0.0821 L·atm/mol·K * 373 K)

n ≈ 0.0082 moles

2. Calculate the molar mass of the compound:

* Molar mass = mass / moles

* Molar mass = 0.800 g / 0.0082 moles

* Molar mass ≈ 97.56 g/mol

3. Determine the empirical formula mass:

* Empirical formula: CHCl

* Empirical formula mass: 12.01 g/mol (C) + 1.01 g/mol (H) + 35.45 g/mol (Cl) = 48.47 g/mol

4. Find the ratio of the molar mass to the empirical formula mass:

* Ratio = Molar mass / Empirical formula mass

* Ratio = 97.56 g/mol / 48.47 g/mol ≈ 2

5. Determine the molecular formula:

* Since the ratio is approximately 2, the molecular formula is twice the empirical formula:

* Molecular formula = (CHCl)₂ = C₂H₂Cl₂

Therefore, the molecular formula of the compound is C₂H₂Cl₂.