Water Purification — Homi Bhabha Class 6 Chemistry MCQs with Solutions
Free Homi Bhabha Class 6 Chemistry Water Purification MCQs with step-by-step solutions (10 questions). Part of Water & Its Management. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Water Purification · easy · theory
Boiling water before drinking makes it safe mainly because it …
A. Kills the germs in the water ✓ Correct
B. Makes the water sweeter
C. Adds salt to the water
D. Turns the water into ice
Solution: The heat of boiling kills the tiny germs (microbes) that cause diseases, so boiled water is safer to drink.
Q2 — Water Purification · easy · theory
Passing muddy water through a clean cloth to remove bits of dirt is an example of …
A. Freezing
B. Evaporation
C. Boiling
D. Filtration ✓ Correct
Solution: The cloth acts like a filter: the solid dirt stays on it while the water passes through. This is filtration.
Q3 — Water Purification · easy · theory
The tiny living things in dirty water that can make us ill are called …
A. Bubbles
B. Pebbles
C. Germs (microbes) ✓ Correct
D. Crystals
Solution: Very small living things called germs or microbes live in dirty water and can cause diseases, so water must be cleaned before drinking.
Q4 — Water Purification · easy · theory
Letting muddy water stand still so that the heavy mud settles at the bottom is called …
A. Sedimentation ✓ Correct
B. Lathering
C. Boiling
D. Chlorination
Solution: When muddy water is left undisturbed, the heavier dirt slowly sinks to the bottom. This settling is called sedimentation.
Q5 — Water Purification · medium · theory
After the mud settles, gently pouring off the clear water without disturbing the sediment is called …
A. Evaporation
B. Transpiration
C. Decantation ✓ Correct
D. Condensation
Solution: Carefully pouring out the clear upper water and leaving the settled dirt behind is called decantation.
Q6 — Water Purification · medium · theory
Which substance is added to the city water supply to kill germs?
A. Oil
B. Soap
C. Sugar
D. Chlorine ✓ Correct
Solution: A small, safe amount of chlorine is added to city water because it kills germs and keeps the water safe to drink.
Q7 — Water Purification · medium · theory
Alum is added to muddy water during purification in order to …
A. Make the water taste sweet
B. Turn the water into vapour
C. Kill all the germs at once
D. Make the fine mud clump together and settle faster ✓ Correct
Solution: Alum makes the tiny mud particles stick together into bigger, heavier lumps that settle quickly, making the water clearer.
Q8 — Water Purification · medium · theory
What is the correct order to clean very muddy pond water for drinking?
A. Boiling → Filtration → Sedimentation
B. Filtration → Boiling → Sedimentation
C. Boiling → Sedimentation → Filtration
D. Sedimentation → Filtration → Boiling ✓ Correct
Solution: First let the mud settle (sedimentation), then filter out the finer bits, and finally boil the water to kill germs.
Q9 — Water Purification · hard · theory
Which of these CANNOT be removed from water by simple filtration?
A. Salt that is dissolved in the water ✓ Correct
B. Sand floating in the water
C. Tea leaves
D. Small pieces of leaf
Solution: Dissolved salt spreads out among the water and passes right through a filter, so filtration cannot remove it. Filtration only removes solid bits that do not dissolve.
Q10 — Water Purification · hard · theory
To get completely pure water from sea water, the water is boiled and the steam is cooled back into liquid. This method is called …
A. Distillation ✓ Correct
B. Sedimentation
C. Sieving
D. Chlorination
Solution: In distillation the water is boiled to steam and then condensed back to liquid. The salts and germs are left behind, so the collected water is very pure.