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6. What water produces an insoluble solid called scale?

  • Temporary hard water
  • Permanent hard water
  • Soft water

7. What dissolved ions make water hard?

  • Magnesium and Fluoride
  • Calcium and magnesium
  • Calcium and carbonate

8. What is used to kill bacteria in a water filter?

  • Flourine
  • Silver
  • Chlorine

9. What is used to kill microbes in drinking water?

  • Chlorine
  • Silver
  • Flourine

10. What is flourosis?

  • When your bones get brittle
  • When your death fall out
  • When your teeth enamel gets destroyed

11. Boiling can soften.....

  • All hard water
  • Temporary hard water
  • Permanent hard water

12. Magnesium compounds reduce heart disease and help to develop strong bones and teeth. True or False

  • False it is both magnesium and calcium ions which do this
  • False it is just calcium ions
  • True

13. To precipitate out the ions that cause hardness you need to add what?

  • Sodium chloride
  • Sodium carbonate
  • Calcium chloride

14. When do hydrocarbonate ions decompose in water?

  • On heating in all hard water
  • On heating in temporary hard water
  • On being in permanent hard water