Question

Which of the following aqueous solution has minimum freezing point?
[1 mark]

• A. $0.01\text{m NaCl}$
• B. $0.005\text{m}{C}_2{H}_{5}OH$
• C. $0.005\text{m}Mg{I}_2$
• D. $0.005\text{m}MgS{O}_4$

Answer 1

The correct option is A $0.01\text{m NaCl}$

Here, $\Delta T_f=i\times K_f\times m$
So, higher is the value $i\times m$, lower id the freezing point of the solution
Here, For $NaCl$, $i=2,m=0.01$
$\therefore i\times m=0.02$
For $C_2{H}_{5}OH$, $i=1,m=0.005$
$\therefore i\times m=0.005$
For $Mg{I}_2$, $i=3,m=0.005$
$\therefore i\times m=0.015$
For $MgS{O}_4$, $i=2,m=0.005$
$\therefore i\times m=0.01$
Thus, $0.01\text{m}NaCl$ has the minimum freezing point.