What happens when water’s salinity increases? mass decreases. freezing point decreases. buoyancy of objects decreases. the amount of dissolved minerals decreases.

Freezing point decreases.

Explanation:

Decreasing of freezing point is a colligative property, which depends on the number of solute particles in the solution. As the number of solute particle increases the freezing point decreases.  

Salt water has a lower freezing point than plain water.  

Salt water does not have a different mass than plain water. Option A is incorrect.

Salt water does not affect the buoyancy or the mineral dissolved in it.  Both option C and D are incorrect