Question

Mole fraction of solute in its 2 molal aqueous solution is

• A. 28.775
• B. 0.034
• C. 0.054
• D. 0.018

Hint:

Mole fraction is a ratio of the number of moles of solute to the total number of moles of solute and solvent.

Answer 1

The Correct Option is B

Step 1: Understanding mole fraction.
Mole fraction is calculated using the formula: \[ \text{Mole fraction of solute} = \frac{\text{moles of solute}}{\text{moles of solute} + \text{moles of solvent}} \] For a 2 molal solution, the molality is 2 moles of solute per 1 kg of solvent. Assuming the density of water is 1 g/mL, 1 kg of water corresponds to 55.5 moles. Thus, the mole fraction of solute can be calculated.

Step 2: Applying the formula.
\[ \text{Mole fraction of solute} = \frac{2}{2 + 55.5} = 0.034 \]
Step 3: Conclusion.
The correct answer is (B) 0.034, which is the mole fraction of solute.