A `10%` solution of urea is isotonic with `20%` solution of `'x'` at same temperature. Calculate molecular weight of `x`.

Explanation

To solve the problem, we need to find the molecular weight of substance 'x' given that a 10% solution of urea is isotonic with a 20% solution of 'x'.

### Step-by-Step Solution:

1. **Understanding Isotonic Solutions**:
- Two solutions are isotonic when they have the same osmotic pressure. Therefore, we can equate the osmotic pressures of the two solutions.

2. **Osmotic Pressure Formula**:
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