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What is the mole fraction of the dissolved substance in a 1.00 molal solution prepared in water?

1. 0.1770
2. 0.0177
3. 0.0344
4. 1.7700

Correct answer: 0.0177

Solution

A 1.00 molal solution has 1 mol solute per 1000 g water = 55.5 mol water. Mole fraction of solute = 1/(1+55.5) = 1/56.5 = 0.0177.

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