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Environmental chemistry: water
5 Class 10 Chemistry questions with answers and explanations.
Printable worksheet with answer key
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Hard water contains dissolved salts of:
- 1 Calcium and magnesium
- 2 Sodium
- 3 Hydrogen
- 4 Potassium only
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Correct answer: Calcium and magnesium
Calcium and magnesium salts cause hardness.
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Temporary hardness is removed by:
- 1 Filtering
- 2 Freezing
- 3 Boiling
- 4 Adding salt
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Correct answer: Boiling
Boiling decomposes calcium hydrogencarbonate and precipitates calcium carbonate.
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Which of these is a water pollutant?
- 1 Nitrogen
- 2 Sewage
- 3 Hydrogen
- 4 Oxygen
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Chlorine is added to drinking water to:
- 1 Make it hard
- 2 Add taste only
- 3 Add colour
- 4 Kill germs
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Soap does not lather easily in:
- 1 Distilled water
- 2 Soft water
- 3 Rain water
- 4 Hard water
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Correct answer: Hard water
Calcium and magnesium ions form scum with soap.