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