Question

Which has the highest freezing point?
A. 1m $K_4[Fe{(CN)}_6]$ solution
B. 1 m $C_6{H}_{12}{O}_6$
C. 1m KCl solution
D. 1m rock salt solution

Answer 1

Hint: Freezing point is one of the colligative properties. The temperature at which a liquid becomes solid is called freezing point. For certain organic compounds like fats, freezing points are lower than the melting point.

Complete answer:
- In the question it is asked to find the chemical which has the highest freezing point among the given options.
- We know that the chemical which produces the minimum number of ions in the aqueous solution results in lowering the freezing point of the solution to the minimum means it has the highest freezing point.
- Coming to the given options, option A. 1m $K_4[Fe{(CN)}_6]$ solution. $K_4[Fe{(CN)}_6]$ produces 5 ions in the aqueous solution.
- Coming to option B, 1m $C_6{H}_{12}{O}_6$ . $C_6{H}_{12}{O}_6$ is a non-electrolyte means it is only going to be a single ion in the aqueous solution.
- Coming to option C, 1m KCl solution. In aqueous solution KCl is soluble and forms two ions.
- Coming to option D, 1m rock salt solution. Rock salt contains a lot of minerals in it means it forms more than two ions when dissolved in an aqueous solution.
- Therefore $C_6{H}_{12}{O}_6$ is the chemical which produces very less number of ions in an aqueous solution and has highest freezing point.

So, the correct option is B.

Note:
As the number ions are going to increase in an aqueous solution the mobility is going to increase and results in an increase in freezing point of the solution then the chemical which forms minimum number ions will have the highest freezing point.