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CBSE 7th Standard Science Wastewater Story Model Questions Papers Study Material - QB365 Set A

Published on: 31/10/2025

Question Set A

CBSE 7th Standard Science Wastewater Story Model Questions Papers Study Material - QB365

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Std: 7th Standard CBSE - Science

chapter: Wastewater Story - Model Questions Papers

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Questions:

Fill up / 1 Marks

5 x 1 = 5

Bacteria play important _______________ in sewage treatment.

Stagnant water blocked in drains is good breeding place for _______________

Vermi-composting toilets use ______________ to treat human waste.

Drains get blocked by ____________ and _____________

Cleaning of water is a process of removing ______________

Generic 3

5 x 3 = 15

What are the different types of inorganic and organic impurities generally present in sewage?

How can we control water pollution?

Give reasons for each of the following.
We should not the drain throw cooking oil and fats down the drain.

Suggest two alternative arrangements for sewage disposal where there is no sewerage system.

10.

Name two chemicals used to disinfect water.

Multiple Choice Question

10 x 1 = 10

11.

The full form of WWTP is:

(a)

Water trickling from a damaged tap

(b)

Water coming out of a shower

(c)

Water flowing in a river

(d)

Water coming out of a laundry

12.

Pick from the following one chemical used to disinfect water:

(a)

Chlorine

(b)

Washing soda

(c)

Silica

(d)

Coal

13.

Chemical used to disinfect water is:

(a)

Chlorine

(b)

Nitrogen

(c)

Methane

(d)

Phosphate

14.

Which of these methods should not be used for disposal of urine and faeces if no sewage system is available?

(a)

Allowing untreated sewage to flow into rivers

(b)

Making septic tanks for sewage to flow into

(c)

Allowing sewage to flow into a biogas plant

(d)

Using a vermi-composting toilet

15.

Which one of the following is a quality of wastewater?

(a)

Fowl smell

(b)

Bad taste

(c)

Dirty look

(d)

All of these

16.

Which of the following is a part of inorganic impurities of the sewage?

(a)

Pesticides

(b)

Urea

(c)

Phosphates

(d)

Vegetable waste

17.

One of the following type of trees are said to help in purifying wastewater quite rapidly when planted all along the sewage ponds. These are

(a)

Eucalyptus trees

(b)

Ficus trees

(c)

neem trees

(d)

peepal trees

18.

Which of the following organisms produce biogas from sludge in the digester tank of a wastewater treatment plant?

(a)

Anaerobic bacteria

(b)

Fungi

(c)

Aerobic bacteria

(d)

Protozoa

19.

Chlorine is used in municipal water treatment plant to

(a)

change the teste of water

(b)

prevent evaporation

(c)

kill the harmful microorganisms

(d)

prevent sedimentation

20.

Study the following statements about ozone.
I. It is essential for breathing of living organisms.
II. It is used to disinfect water.
III. It absorbs ultraviolet rays.
IV. Its proportion in air is about 3%.
Which of these statements are correct?

(a)

I, II and III

(b)

II and III

(c)

I and IV

(d)

All of these

Generic 2

5 x 2 = 10

21.

Why you are advised not to throw soft toys, used tea leaves, cotton and sanitary towels into drains?

22.

Sanitation can be improved. Explain, what step should be taken to improve it.

23.

Bleaching powder is mixed in water, why? Think and give appropriate reason for it.

24.

Name two things that can be made from sludge extracted during treatment of sewage.

25.

Name two chemicals used to disinfect wastewater.

Generic 5

2 x 5 = 10

26.

Describe various house-keeping practices for efficient working of sewage system.

27.

One day Sachin had gone to his uncle who lives in a village. He saw there a large number of people defecate in an open area because proper toilet facilities are not there. He wondered about the groundwater contamination, as he studied in his class that this act may cause water-borne diseases. He convinced village people to make toilets to avoid such an out break of water-borne diseases.
(a) Name two water-borne diseases.
(b) Explain vermi-composting toilets.
(c) What values are shown by Sachin?

1 Marks

5 x 1 = 5

28.

Contaminated water is a potential health hazard. Name any two diseases that could be caused by consumption of contaminated water.

29.

How can we make water clean?

30.

What is waste water?

31.

What is the function of a skimmer in a water treatment plant?

32.

What is a chemical toilet?

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Answers Key:

Fill up / 1 Marks

5 x 1 = 5

()
role

()
insect vectors

()
earthworms

()
solid food remains, oil and fats

()
pollutants

Generic 3

5 x 3 = 15

(i) Inorganic impurities - nitrates, phosphates and metals.
(ii) Organic impurities - fruit and vegetable wastes, oil, urea, human faeces, animal waste, pesticides and herbicides

We can control pollution by following measures:
(i)By avoiding disposal of industrial and household wastes into river water.
(ii)By avoiding washing of clothes, cleaning utensils and bathing with soap near the source of water.
(iii) By covering the mouth of well so that dust, leaves etc., may not fall into it.

We should not throw cooking oil and fats down the drain as it can harden and block the drain-pipes.

The two alternative arrangements for sewage disposal, where there is no sewerage system are as below (i) Septic tanks (ii) Composting pits.

10.

Two chemicals used to disinfect water are chlorine and ozone.

Multiple Choice Question

10 x 1 = 10

11.

(d)
Water coming out of a laundry

12.

(a)
Chlorine

13.

(a)
Chlorine

14.

(a)
Allowing untreated sewage to flow into rivers

15.

(d)
All of these

16.

17.

(a)
Eucalyptus trees

18.

(a)
Anaerobic bacteria

19.

20.

(b)
II and III

Generic 2

5 x 2 = 10

21.

Such wastes choke the drains. They do not allow free flow of oxygen. This hampers the degradation process.

22.

Low cost onsite sewage disposal system must be encouraged to improve sanitation.

23.

Bleaching powder is mixed in water to make it safe for drinking because it kills the harmful germs present in water.

24.

Biogas and manure.

25.

Chlorine and ozone

Generic 5

2 x 5 = 10

26.

(i) Left overfood contains lot of oil and fat, it should not be thrown down the drain. They choke the pipe when they become harden. These waste when thrown in open drains block the oil pores thereby decreasing its effectiveness to filter water. Such wastes should be thrown in dustbin only.
(ii) Solid wastes such as used tea leaves, plastic bags, soft toys, cotton and sanitary towels should not be thrown in drains. Such wastes block the drain. They reduce free flow of oxygen and thus slow down the process of degradation.
(iii) Chemical products like medicines, motor oil, paint, machine oil and insecticide should also be not thrown down the drain. These substances kill water purifying organisms and hamper degradation.

27.

(a) Typhoid and cholera.
(b) In vermi-composting toilets, human excreta is treated by earthworms in a pit.
(c) He is intelligent and concious about health

1 Marks

5 x 1 = 5

28.