PSEB Class 7 Science Chapter 18 Waste Water Story Solution

PSEB Class 7 Science Chapter 18 Waste Water Story SolutionPSEB Punjab Board Class 7 Science Textbook Solution Chapter 18 Waste Water Story Exercise Questions and Answers



Chapter 18 Waste Water Story

Q.1 Fill in the blanks:

(i) ……………….. are dissolved and suspended solid impurities present in sewage.

Answer: Pollutants.


(ii) The activated sludge is about ……………….. water.

Answer: 97%.


(iii) …………………. is the solid material settled at the bottom of water clarifier.

Answer: Sludge


(iv) ……………… is the place where contaminants are removed from wastewater.

Answer: Water purification tank


(v) Adopt ……………….. sanitation practices.

Answer: Good


Q.2 True or false:

(i) The sight and smell of open drain is attractive.

Answer: False


(ii) Throw plastic bags in the drain.

Answer: False


(iii) Open drain is the breeding place for flies and mosquitoes.

Answer: True


(iv) Do not defecate in the open.

Answer: True


(v) Solid food remains can block the drains.

Answer: True


Q.3 Match the following


1. Organic impurities :- e. Human wastes.

2. Inorganic impurities :- d. Nitrates and phosphates.

3. Wastewater treatment :- a. Sewage treatment.

4. Water borne disease :- b. Typhoid.

5. Dried sludge :- c. Manure.


Q.4 Choose the correct answer.

i) Wastewater treatment plant involve:

a) Bar screen

(b) Water clarifier

(c) Grit and sand removal tank

(d) All of these.

Answer: (d) All of these.


(ii) Name the by-product of wastewater treatment plant:

(a) Biogas.

(b) Sludge

(c) Both (a) and (b)

(d) None of these.

Answer: (c) Both (a) and (b)


(iii) Which of the following chemicals is used to disinfect water ?

(a) Chlorine

(b) Ozone

(c) Both (a) and (b)

(d) None of these.

Answer: (c) Both (a) and (b).


(iv) World Toilet Day is celebrated every year on:

(a) 29 November

(b) 19 October

(c) 19 November

(d) 29 October.

Answer: (c) 19 November.


(v) Which of the following is not a low cost onsite sewage disposal system

(a) Septic tank

(b) Compost pit

(c) Chemical toilets

(d) Bar screen.

Answer: (d) Bar screen



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Updated: August 24, 2022 — 10:58 pm

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