Question

Maximum depression in freezing point is caused by:
A) Potassium Chloride
B) Sodium sulphate
C) Magnesium sulphate
D) Magnesium carbonate

Answer 1

Hint: In the given question we will understand how the depression in the freezing point occurs and which compounds among the following have caused the highest depression in the freezing point. As the depression of freezing point is a colligative property.

Complete answer:
Although Freezing-point depression is stated as the decrease of the freezing point of a particular solvent on the addition of a particular non-volatile solute, such as alcohol in water and salt in water.
Accordingly, a depression in the freezing point is a colligative property, consequently it depends upon the number of particles.

So among the given compounds, potassium chloride\[\left( {KCl} \right)\], sodium sulphate \[\left( {N{a_{2}}S{O_4}} \right)\],magnesium sulphate \[\left( {MgS{O_4}} \right)\;\]and magnesium carbonate \[\left( {MgC{O_3}} \right)\],\[N{a_2}S{O_4}\] ​ produces maximum number of particles.
\[N{a_2}S{O_4}\; \rightleftharpoons 3particles2N{a^{ + + }} + S{O_4}^{2 - }\]
Thus, it causes maximum depression in the freezing point.

As Freezing-point depression might as well be used as a purity analysis instrumental tool as when analyzed by a differential scanning calorimetry method. Therefore, the results obtained are in mol percentage, nevertheless the technique has its place, where other methods and approaches of analysis fail.

Hence, the correct answer is option ‘B’.

Note:The freezing-point depression has many real-world uses such as it used in the radiator fluid in an automobile as it is a mixture of water and ethylene glycol. Road salting takes benefit of this effect to lower the freezing point of the ice so it has been placed on it.