The density of the vapour of a substance at 373 K and `1.013 xx 10^(5)` Pa is 2.55 g/lit. Calculate its molecular weight.

Explanation

To calculate the molecular weight of the vapor of a substance given its density, temperature, and pressure, we can use the formula derived from the ideal gas law. Here’s a step-by-step solution:

### Step 1: Write down the formula for molecular weight
The molecular weight (M) can be calculated using the formula:
\[ M = \frac{D \cdot R \cdot T}{P} \]
where:
- \( D \) is the density of the vapor (in g/L),
- \( R \) is the ideal gas constant,
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