Question

Find the mole fraction of water present in 3 molal aqueous solution of NaOH.

• A. 0.65
• B. 0.95
• C. 0.32
• D. 1.68

Answer 1

The correct option is B 0.95

3 molal aqueos solution means 3 moles of NaOH (solute) is present in 1000 g of water (solvent)
Number of moles of water $=\frac{1000}{18}=55.56$
$Molefraction\left(solvent\right)=\frac{molesofsolvent}{molesofsolute+molesofsolvent}$
Mole fraction of water $=\frac{55.56}{55.56+3}=\frac{55.56}{58.56}=0.95$