Question

Match the following aqueous solutions with the appropriate letter from the column on the right. Assume complete dissociation of electrolytes.

	1.	0.28 m	KI		A.	Lowest freezing point
	2.	0.12 m	Na3PO4		B.	Second lowest freezing point
	3.	0.17 m	CuCl2		C.	Third lowest freezing point
	4.	0.53 m	Urea (nonelectrolyte)		D.	Highest freezing point

Answer 1

As the salt added to water, it decreases its freezing point . The extent of decrement depends on the no. of ions produce after dissociation of salt (electrolyte).

So, Na3PO4 aqueous solution has lowest freezing point because it will form 4 ions ( 3Na+ & 1 PO43-) after dissociation.

CuCl2 aqueous solution has second lowest freezing point because it will form 3 ions ( 1 Cu+ & 2 Cl-) after dissociation.

KI aqueous solution has third lowest freezing point because it will form 2 ions ( 1 K+ & 1 I-) after dissociation.

Urea solution which is a non-electrol has highest freezing point because it doesn't dissociate to give ions.