Question

The mole fraction of the solute in 2.5 molal aqueous solution is:

• A. 0.051
• B. 0.43
• C. 0.043
• D. 0.156

Answer 1

The correct option is C 0.043

2.5 molal $\Rightarrow$ 2.5 moles of solute in 1000 g of solvent
Number of moles of solute = 2.5 mol
Number of moles of solvent = $\frac{1000}{18}=55.56$ mol
Mole fraction of the solute = $\frac{2.5}{2.5+55.56}=0.043$