Q. Which one is a colligative property?
A) Raoult’s law states that the vapour pressure of a component over a solution is proportional to its mole fraction
B) The osmotic pressure ($\pi$)of a solution is given by the equation$\ \ \pi$ = MRT, where , M is the molarity of the solution
C) The correct order of osmotic pressure for 0.01 M aqueous solution of each compound is $BaCl_{2} > KCl > CH_{3}COOH >$ sucrose
D) Two sucrose solutions of same molality prepared in different solvents will have the same freezing point depression
Explanation
(d)
$P_{A} = X_{A}p_{A}^{{^\circ}}\ true$
$\pi = iMRT = MRT\ true\ (if\ van^{'}t\ Hoff\ factor\ i = 1)$
i=[1+(y-1)x]
y= number of ions,
x = degree of ionization,
i=3 for $BaCl_{2}x$=1(strong electrolyte)
i=(1+x) for $CH_{3}COOH\ x \ll 1(weak)$
i=1for sucrose (non-electrolyte)
i(for$BaCl_{2})$ >KCl>$CH_{3}COOH > sucrose\$
Thus ,(c) is also true.
$\mathrm{\Delta}T_{f} = k_{f}m$
$k_{f}$ is dependent on solvent
Thus, freezing points [=T(solution)-$\mathrm{\Delta}T_{f})$ are different.
Thus, (d) is false.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.