Judgement: If the laboratory evaporates a sodium chloride solution to precipitate crystals, the mass fraction of the solute must be reduced. Judgement: The laboratory evaporates a sodium chloride solution to precipitate crystals, and the mass fraction of the solute must be reduced.

Judgement: If the laboratory evaporates a sodium chloride solution to precipitate crystals, the mass fraction of the solute must be reduced. Judgement: The laboratory evaporates a sodium chloride solution to precipitate crystals, and the mass fraction of the solute must be reduced.

In the laboratory, a sodium chloride solution is evaporated to precipitate crystals, and the mass fraction of the solute may increase or remain unchanged. If it is a saturated solution, the crystals will be precipitated after evaporation. If the mother solution is a saturated solution, the mass fraction will remain unchanged; if it is an unsaturated solution, the mass fraction of the solute in the mother solution will remain unchanged after evaporation.

In the laboratory, a sodium chloride solution is evaporated to precipitate crystals, and the mass fraction of solute may increase or remain unchanged. If it is a saturated solution, the crystals will be precipitated after evaporation. If the mother solution is a saturated solution, the mass fraction will remain unchanged; if it is an unsaturated solution, the mass fraction of solute in the mother solution will remain unchanged after evaporation.

1.2 G salt crystals were obtained by evaporating 15 g salt solution, and the mass fraction of solute in the original salt solution was calculated 1.2 G of salt crystal was obtained by evaporating 15 g of salt solution, and the mass fraction of solute original salt solution was calculated

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