Environmental chemistry: water

Class 10 · Chemistry · 5 questions

Name: ____________________ Date: ____________

Hard water contains dissolved salts of:
- A Calcium and magnesium
- B Sodium
- C Hydrogen
- D Potassium only
Temporary hardness is removed by:
- A Filtering
- B Freezing
- C Boiling
- D Adding salt
Which of these is a water pollutant?
- A Nitrogen
- B Sewage
- C Hydrogen
- D Oxygen
Chlorine is added to drinking water to:
- A Make it hard
- B Add taste only
- C Add colour
- D Kill germs
Soap does not lather easily in:
- A Distilled water
- B Soft water
- C Rain water
- D Hard water

Answer key

1. A, 2. C, 3. B, 4. D, 5. D

Calcium and magnesium salts cause hardness.
Boiling decomposes calcium hydrogencarbonate and precipitates calcium carbonate.
Untreated sewage pollutes water.
Chlorination disinfects water.
Calcium and magnesium ions form scum with soap.