The vapour pressure of benzene at `90^(@)C` is `1020` torr. A solution of `5g` of a solute in `58.5g` benzene has vapour pressure 990 torr. The molecular weight of the solute is?

Explanation

To find the molecular weight of the solute, we can use Raoult's law and the formula for calculating the molecular weight based on vapor pressure changes. Here’s a step-by-step solution:

### Step 1: Identify the given values
- Vapor pressure of pure benzene (P₀) = 1020 torr
- Vapor pressure of the solution (Pₛ) = 990 torr
- Mass of solute (Wₐ) = 5 g
- Mass of solvent (Wₛ) = 58.5 g
- Molecular weight of benzene (Mₛ) = 78 g/mol
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