Question

An ice-skating rink has tubes under its floor to freeze the water. salt water is cooled well below the freezing point of water and pumped through the tubes to freeze the water in the rink. why can the salt water be cooled so low without freezing? f salt has a very low freezing point. g adding salt to water lowers its freezing point. h the salt water is constantly absorbing energy from its surroundings. j movement of the salt water through the tubes keeps it in the liquid state.

Answer 1

Correct Answer: Option g: adding salt to water lowers its freezing point

Reason:
Freezing point is a colligative property. When a non-volatile solution is present in solution, it's freezing point decreases. This is referred as depression in freezing point (ΔTf). Extent of lowering in freezing point is dependent on number of particles present in system. Mathematically it is expressed as:

ΔTf = Kf X m

where, m = molality of solution
Kf = cryoscopic constant. 

Hence, adding salt to water lowers the freezing point of solution.