Calculate wt of urea which must be dissolved in `400gm` of water so final solutions has `V.P.2%` less than `V.P.` of pure water:

Explanation

To solve the problem of calculating the weight of urea that must be dissolved in 400 g of water so that the final solution has a vapor pressure that is 2% less than that of pure water, we can follow these steps:

### Step 1: Understand the Vapor Pressure Reduction
The vapor pressure of the solution is 2% less than that of pure water. If we denote the vapor pressure of pure water as \( P_0 \), then the vapor pressure of the solution \( P \) can be expressed as:
\[ P = P_0 - 0.02 P_0 = 0.98 P_0 \]

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