Hot tubs generally contain water at a temperature of 38°C to keep the water clean several solid solute's are dissolved in the water . Many hot tub manufacturers warn that if the water gets too cold it will get cloudy and Fill with a fine solid why?

Because allowing the water to get too cold implies that some precipitate will be formed.

Explanation:

If you allow the hot tub to cool down, there will be a reduction in the solubility of the solutes. In this light, if its then get too could, the solubility of the solutes will be so low in such a way that it becomes inevitable that some of the solute must then leave the solution, hence creating a precipitate which is the fine solid that has been mentioned in the question.

your answer would be a. 12.5 kg