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True or false? Using hard water makes it more difficult for soap to lather.
Which of these rocks helps to cause hardness in water?
Which type of deposit forms when hard water reacts with soap?
Scale, calcium carbonate
Scum, calcium stearate
Which type of deposit forms when hard water is boiled?
True or false? Calcium carbonate dissolves in carbonic acid (rainwater) to produce calcium ions and hydrogencarbonate ions.
Which type of hard water can be softened by heating?
Permanent hard water
Temporary hard water
True or false? Scale is formed upon heating temporary hard water because calcium hydrogencarbonate forms a precipitate.
Which of these methods can soften either type of hard water?
Which ion is exchanged with calcium and magnesium ions in an ion-exchange column?
True or false? Ion-exchange columns do not need to be regularly washed out with saline solution.
What is the first stage in the water treatment process?
Passing water through a sand filter for clear water
Passing water through metal meshes to remove large objects
Chlorination of water to kill bacteria
Adding aluminium sulphate and lime to encourage flocculation of suspended particles in the water
What is the second stage in the water treatment process?
What is the third stage in the water treatment process?
What is the fourth stage in the water treatment process?
What is often contained in a filter cartridge?
What are health benefits of drinking hard water?
Reduced risk of heart disease
Reduced risk of cancer
Stronger bones and teeth
Which gas is sometimes used as an alternative to chlorine in killing bacteria?
Which ion is sometimes added to water to reduce the risk of tooth decay?
Which of these are arguments for the fluoridation of water?
Reduction in tooth decay
Increased risk of fluorosis
Protects people who don't have good dental hygiene
Impossible to set safe limits due to varied intake
Ethical issues of being forced to take a treatment
Which of these are arguments against the fluoridation of water?
Protects people who do not have good dental hygiene
Ethical issues with being forced to take a treatment