If you are looking for DAV Class 4 Science Chapter 9 Question Answer Safe Handling and Storage of Water of My Living World science book, then you are at the right place. Here at NCERTBooksPDF, Class 4 Science Chapter 9 exercises are solved with accurate, child-friendly explanations, clear purification comparisons, and complete solutions to help DAV students score top marks in their exams.
Table of Contents
- DAV Class 4 Science Chapter 9 Safe Handling of Water Solutions
- A. Fill in the Blanks
- B. Write True or False (With Explanations)
- C. Tick the Correct Option
- D. Answer the Following Questions in Brief
- E. Answer the Following Questions (Detailed Explanations)
- Value-Based Questions
- Something to Do
DAV Class 4 Science Chapter 9 Safe Handling of Water Solutions
DAV Class 4 Science Chapter 9 Safe Handling and Storage of Water covers potable water standards, water purification methods (filtration, boiling, chlorination), water-borne diseases, safe storage, and mosquito prevention in stagnant water. Below are the complete textbook solutions.
A. Fill in the blanks.
1. Water, which is fit for drinking, is called potable water.
2. Ground water is not fit for drinking because it contains dissolved salts and germs.
3. Filtration removes dust from water.
4. Boiling and chlorination kill germs present in water.
5. Water should always be stored in clean and covered utensils.
Answer: (1) potable water | (2) dissolved salts, germs | (3) Filtration | (4) Boiling, chlorination | (5) clean, covered
B. Write True or False for the following statements.
1. We should always store drinking water in covered clean containers.
Answer: True
Reason: Clean lids prevent dust, flies, and airborne pathogens from settling into drinking water.
2. We can drink water that has been stored for many days.
Answer: False
Reason: Water left stagnant for prolonged days can accumulate bacterial growth and becomes unhygienic.
3. We need to purify water before drinking it.
Answer: True
Reason: Untreated water can carry microscopic bacteria, parasites, and chemical impurities that cause severe infections.
4. We can allow water to stagnate around our house.
Answer: False
Reason: Stagnant water is a prime breeding ground for female mosquitoes that spread deadly dengue and malaria.
5. We should use a ladle to take out water from a container.
Answer: True
Reason: Using a clean, long-handled ladle keeps hands and fingernails from touching and contaminating the drinking water.
C. Tick (✓) the correct option.
1. Germs, present in water, may be killed by—
(a) simple filtration
(b) storing it in covered containers
(c) storing it for many days
(d) chlorination
Answer: (d) chlorination
Explanation: Chlorination is a chemical disinfectant method that destroys bacteria and microbial pathogens. Simple filtration only strains out suspended dirt.
2. By drinking unclean water, one may get a disease like—
(a) malaria
(b) dengue
(c) chikungunya
(d) jaundice
Answer: (d) jaundice
Explanation: Jaundice (Hepatitis A) is a water-borne illness caused by ingesting contaminated drinking water, whereas malaria and dengue are spread by mosquito bites.
3. Dust and other suspended particles present in unclean water can be removed by—
(a) boiling
(b) keeping it in a fridge
(c) filtration
(d) chlorination
Answer: (c) filtration
Explanation: Filtration uses physical porous barriers (cloth, sand, membrane) to trap and filter out insoluble suspended particles and dirt.
4. Our body requires, and uses, water for—
(a) breathing
(b) digestion of food
(c) preparation of food
(d) transpiration
Answer: (b) digestion of food
Explanation: Water dissolves food substances, transports nutrients across intestinal membranes, and facilitates digestion.
D. Answer the following questions in brief.
1. State the meaning of the term ‘potable water’.
Answer: Water that is clear, clean, free from disease-causing germs, and completely safe and wholesome for human drinking is called potable water.
2. Name any two diseases that can be caused by drinking unclean water.
Answer: Jaundice and Cholera (or Typhoid and Diarrhea).
3. Name the diseases which are spread by mosquitoes.
Answer: Malaria, Dengue, and Chikungunya.
4. How does boiling help in making water safer for drinking?
Answer: Boiling water at 100°C for 10 to 15 minutes destroys all harmful bacteria, viruses, and microbial germs present in it, rendering it microbiologically safe to drink.
5. Name two methods of purification of water.
Answer: Boiling and Chlorination (or modern RO/UV filtration).
6. State any two ways of safe handling of drinking water.
Answer:
(i) Always store drinking water in clean, sterilized containers covered with tight-fitting lids.
(ii) Never dip bare hands or unwashed glasses into the water container; always use a clean ladle with a long handle or draw water from a tap.
E. Answer the following questions.
1. Why should water be purified before drinking?
Answer: Water from natural and tap sources often contains invisible pathogens (bacteria, protozoa, viruses), suspended dust, and dissolved chemical impurities. Drinking unpurified water can lead to dangerous water-borne epidemics like cholera, diarrhea, hepatitis, and typhoid. Therefore, water must be thoroughly purified before consumption.
2. What is chlorination? How does it purify water?
Answer: Chlorination is the method of disinfecting drinking water by adding a measured dose of chlorine tablets, liquid chlorine, or bleaching powder. Chlorine acts as a powerful germicide that kills bacteria, parasites, and other disease-causing germs, making large water supplies potable.
3. Why is the traditional method of filtration not completely sufficient for making water fit for drinking?
Answer: Traditional filtration (using clean cloth, sand-gravel beds, or ceramic candle filters) only strains out visible, suspended solid dust, mud, and dirt particles. It cannot remove dissolved chemical impurities or kill microscopic disease germs and viruses. Hence, traditional filtration must be coupled with boiling or chlorination.
4. Why should we not allow water to stagnate around our houses?
Answer: Stagnant water in pools, discarded coolers, broken clay pots, old vehicle tyres, and open ditches becomes a fertile breeding ground for female mosquitoes. Aedes and Anopheles mosquitoes lay eggs in stagnant water, leading to rapid mosquito proliferation and outbreaks of dengue, malaria, and chikungunya.
5. State two ways that can be used to prevent breeding of mosquitoes in room coolers.
Answer:
(i) Empty, clean, and thoroughly dry the water tank of room coolers once every week before refilling with fresh water.
(ii) Pour two tablespoons of kerosene oil or a few drops of larvicide oil into the cooler tank if the water cannot be replaced immediately; the oil film suffocates mosquito larvae by cutting off air contact.
Value-Based Questions
One day Dr. Nishant Narang, a friend of Mr. Chanderkant, visited his home. He noticed a pool of stagnant water outside the house. He told Mr. Chanderkant that this stagnant water was an active breeding place for mosquitoes that cause dangerous diseases like malaria and dengue. Mr. Chanderkant realised his mistake and promised to ensure that water never stagnates in his neighbourhood.
1. Point out the lack of values displayed by Mr. and Mrs. Chanderkant.
Answer: They displayed carelessness, lack of civic hygiene awareness, and neglect towards community public health by ignoring stagnant water outside their house.
2. State the values displayed by Dr. Narang.
Answer: Dr. Narang displayed alertness, professional responsibility, civic sense, and genuine care for the well-being and health of his friend’s family and neighborhood.
3. Suggest some ways to ensure that there is no stagnation of water around Mr. Chanderkant’s house.
Answer:
- Fill up low-lying potholes, trenches, and ditches around the home with sand and soil.
- Ensure neighborhood open drains are cleaned and have a continuous slope so water flows freely without clogging.
- Regularly check and discard collected rainwater from broken buckets, coconut shells, and old tires.
Something to Do
1. Home Water Purification Audit: Inspect your home water purifier (UV, RO, or boiling). Understand how filters remove suspended dirt and how UV/boiling neutralizes microorganisms.
2. Anti-Mosquito Neighborhood Drive: Conduct a weekend check with your family to ensure air coolers, plant saucers, and overhead tanks are properly sealed and covered.
Related Chapters:
- DAV Class 4 Science Solutions (All Chapters)
- DAV Class 4 Science Chapter 8 Water Scarcity
- DAV Class 4 Science Chapter 10 Water Pollution
🎉 Chapter 9 Completed!
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