• # question_answer The vapour pressure of pure liquid solvent A is $0.80$ atm. When a non-volatile substance B is added to the solvent, its vapour pressure drops to $0.60$atm. What is the mole fraction of component B is the solution? A)  $0.75$                       B)  $0.25$C)  $0.40$                       D)  $0.60$

$P={{X}_{A}}{{P}^{o}}$ ${{X}_{A}}=\frac{P}{{{P}^{o}}}=\frac{0.60\,atm}{0.80\,atm}=0.75$ ${{X}_{B}}=1-0.75=0.25$