Final answer:
Temporary hard water contains calcium or magnesium salts that can be removed by boiling, whereas permanent hard water has calcium or magnesium ions that remain dissolved.
Step-by-step explanation:
The question is related to the differences between temporary hard water and permanent hard water. Temporary hard water contains calcium or magnesium compounds that can be precipitated out from the water by boiling. On the other hand, permanent hard water contains calcium or magnesium compounds that do not precipitate out of the water even upon boiling.
Therefore, the correct answer to fill in the blanks is: Temporary hard water contains Ca or Mg salts that can be precipitated out from the water by boiling. Permanent hard water contains Ca or Mg ions that do not precipitate out of the water. So the correct answer is C) Salts, ions.