Water Purification — Homi Bhabha Class 9 Chemistry MCQs with Solutions
Free Homi Bhabha Class 9 Chemistry Water Purification MCQs with step-by-step solutions (8 questions). Part of Substances in Daily Use & Applied Chemistry. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Water Purification · medium · theory
The settling down of heavy insoluble impurities in water on standing is called:
A. aeration
B. sedimentation ✓ Correct
C. evaporation
D. chlorination
Solution: In sedimentation, suspended solid impurities settle at the bottom.
Q2 — Water Purification · hard · theory
Chlorine is added to drinking water in a treatment plant mainly to:
A. add taste
B. kill disease-causing germs ✓ Correct
C. increase hardness
D. remove colour only
Solution: Chlorination disinfects water by killing bacteria and other pathogens.
Q3 — Water Purification · medium · theory
A simple household method to make water safe for drinking by killing microbes is:
A. colouring
B. shaking
C. freezing
D. boiling ✓ Correct
Solution: Boiling water kills most disease-causing microorganisms, making it safer to drink.
Q4 — Water Purification · hard · theory
Reverse osmosis (RO) purifiers are used mainly to remove:
A. dissolved salts and impurities ✓ Correct
B. only large solid particles
C. only colour
D. oxygen
Solution: RO forces water through a semipermeable membrane, removing dissolved salts and fine impurities.
Q5 — Water Purification · medium · theory
Water that is safe and fit for drinking is described as:
A. distilled sea water only
B. hard water only
C. potable water ✓ Correct
D. polluted water
Solution: Potable water is clean water that is safe to drink.
Q6 — Water Purification · easy · theory
At a municipal water works, a small amount of chlorine is added to the water mainly to
A. increase the hardness of the water
B. change the colour of the water
C. kill the disease-causing germs present in the water ✓ Correct
D. give the water a sweeter taste
Solution: Chlorine is added as a disinfectant. It kills bacteria and other disease-causing microbes, making the water safe to drink. This step is known as chlorination.
Q7 — Water Purification · medium · theory
While purifying river water for supply, large suspended particles are first allowed to settle at the bottom of a tank. This step is called
A. sedimentation ✓ Correct
B. chlorination
C. distillation
D. aeration
Solution: Allowing heavy suspended particles to settle down under gravity in a tank is called sedimentation. It is usually followed by filtration and then chlorination to make the water fit for drinking.
Q8 — Water Purification · hard · theory
A sample of muddy water is passed through a cloth filter and then boiled. Which impurity is still most likely to remain in it?
A. dissolved common salt ✓ Correct
B. floating leaves
C. large grains of sand
D. suspended mud particles
Solution: Filtering removes suspended solids such as sand, mud and leaves, and boiling kills germs, but neither of these removes dissolved salts. Common salt stays dissolved and can be separated only by methods like distillation or reverse osmosis.