CBSE Class 7 Science Waste Water Story Assignment

L-18 A Waste Water Story

Q.1 Fill in the blanks :
1. The impurities like lather, oil, urea, dirt etc. Which are dissolved and suspended in sewage are called contaminants.
Answer: Contaminants
In simple words: Impurities mixed in water are called contaminants.

Exam Tip: Remember that any unwanted substance in water is a contaminant.

2. The set of pipes which take away sewage from our homes to the water treatment plants are called __________.
Answer: Sewerage
In simple words: A network of pipes carrying sewage is known as sewerage.

Exam Tip: Do not confuse 'sewer' (the pipe) with 'sewerage' (the network of pipes).

3. __________ is wastewater released by homes, industries, hospitals etc.
Answer: Sewage
In simple words: Wastewater coming from various sources is called sewage.

Exam Tip: Sewage is liquid waste rich in water and impurities.

4. __________ trees are planted all along sewage ponds.
Answer: Eucalyptus
In simple words: Eucalyptus trees absorb surplus wastewater rapidly.

Exam Tip: Eucalyptus trees act as natural purifiers because they consume large amounts of water.

5. Wastewater is treated in a __________ treatment plant.
Answer: Sewage (or Wastewater)
In simple words: Wastewater is cleaned in a specialized treatment plant.

Exam Tip: Commonly abbreviated as WWTP (Wastewater Treatment Plant).

Q.2 Complete the chart :
Answer:
Water can be used for various purposes such as: Drinking, Cooking, Cleaning, Bathing, Gardening, and Washing.
In simple words: Water has multiple daily domestic and industrial uses.

Exam Tip: Draw clear branching arrows from the central box to each use in exam charts.

Q.3 Identify the following statements as "Do's and Don'ts" for better housekeeping practice :
1. Cooking oil and fats should be thrown down the drain.
Answer: Don't
In simple words: Oils and fats choke drains and block pipes.

Exam Tip: Always throw solid fats and oils in the dustbin, never in sinks.

2. Chemicals like paints, solvents, insecticides, medicines, motor oil may kill microbes that help to purify water, so do not throw them down the drain.
Answer: Do
In simple words: The statement advises correct action (not throwing chemicals down the drain), hence it is a good practice (Do).

3. Used tea leaves, solid food remains, soft toys, cotton, sanitary towels etc. should be thrown in the drains.
Answer: Don't
In simple words: Solid waste chokes drainage pipes.

Exam Tip: Solids should always go into municipal solid waste bins.

4. The untreated human excreta is a health hazard, thus toilets should be constructed to maintain personal hygiene.
Answer: Do
In simple words: Safe sanitation prevents diseases.

Exam Tip: Proper sanitation is essential for public health.

5. Cleaning and wiping floors everyday is not necessary at all.
Answer: Don't
In simple words: Floors must be cleaned regularly to maintain hygiene.

Exam Tip: Regular cleaning keeps germs and disease vectors away.

L-18 A Waste Water Story

Q.1 Here is a crossword puzzle : Good Luck !
CLUE --
1. Used water _____________.
Answer: Wastewater
In simple words: Water that has been used is wastewater.

Exam Tip: Look across the first row of the puzzle grid.

2. Liquid waste products ______________.
Answer: Sewage
In simple words: Liquid waste is called sewage.

Exam Tip: Sewage flows through underground pipes.

3. Pipe carrying sewage ______________.
Answer: Sewer
In simple words: A pipe for carrying sewage is a sewer.

Exam Tip: Singular pipe is sewer, network is sewerage.

4. Absorbs Ultraviolet rays _________________.
Answer: Ozone
In simple words: Ozone layer absorbs harmful UV rays.

5. Used to disinfect water ________________.
Answer: Chlorine
In simple words: Chlorine kills germs in water.

Exam Tip: Chlorine tablets are commonly used for purification.

6. Solid waste extracted in sewage treatment ____________.
Answer: Sludge
In simple words: Settled solid waste is sludge.

Exam Tip: Sludge is decomposed by anaerobic bacteria.

7. Waste matter discharged from human body _______________.
Answer: Excreta
In simple words: Human waste is known as excreta.

Exam Tip: Untreated excreta is a major health hazard.

8. Suspended and dissolved impurities in water ______________.
Answer: Contaminants
In simple words: Impurities present in water are contaminants.

Exam Tip: Contaminants make water unsafe for drinking.

9. Trees planted along sweage ponds _________________.
Answer: Eucalyptus
In simple words: Eucalyptus absorbs excess wastewater.

Exam Tip: High transpiration rate makes Eucalyptus ideal near ponds.

Q.2 Write one slogan on "Conservation of water".
Answer: Save water today, survive tomorrow! / Water is life, conserve every drop.
In simple words: Catchy phrases encourage people to save water.

Exam Tip: Keep slogans short, rhyming, and impactful.