Question

$0.01 \,M$ solution has $3\%$ sucrose, $4\% BaCl_{2}$, $2\% KCl$ and $1\% FeCl_{3}$. Then the correct order of freezing point at $1 $ atm pressure

• A. $Sucrose < \,KCl< \,BaCl_{2} <\, FeCl_{3}$
• B. $FeCl_{3} <\, BaCl_{2} <\, KCl< \, Sucrose$
• C. $BaCl_{2} <\, FeCl_{3} <\, Sucrose < \,KCl$
• D. $KCl< \,Sucrose <\, FeCl_{3} < \,BaCl_{2}$

Answer 1

Answer: (B)

Depression in freezing point is directly proportional to van't Hoff factor i and i is directly proportional to number of ions furnished by a molecule. Higher the ions furnished, higher is the depression in freezing point and so lower is the freezing point
Compound i
Sucrose = 1
$BaCl_{2}=3$
$KCl=2$
$FeCl_{3}=4$
So, the order of freezing point is
$FeCl_{3}<\,KCl<\,BaCl_{2}<\, {\text{sucrose}}$