CBSE Class 7 Science Waste water Story VBQs

Choose The Correct Answer.

Question. Wastewater treatment plant involves:
a) Bar screen
b) Water clarifier
c) Grit and sand removal tank
d) All of these
Answer : D

Question. Name the by-product of wastewater treatment plant:
a) Biogas
b) Sludge
c) Both a and b
d) None of these
Answer : C

Question. Which of the following chemical is used to disinfect water:
a) Chlorine
b) Ozone
c) Both a and b
d) None of these
Answer : B

Question. World toilet day is celebrated every year on:
a) 29 November
b) 19 October
c) 19 November
d) 29 October
Answer : C

Question. 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

.

Fill In The Blanks :

(i). Contaminants are dissolved and suspended sold impurities present in sewage.

(ii). The activated sludge is about 97% water.

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

(iv). Waste water treatment plant is the place where contaminants are removed from wastewater.

(v). Adopt good sanitation practices.

Write True Or False.

Question. The sight and smell of open drain is attractive.
Answer : False

Question. Throw plastic bags in the drain. 
Answer : False

Question. Open drain is the breeding place for flies and mosquitoes.
Answer : True

Question. Do not defecate in the open.
Answer : True

Question. Solid food remains can block the drain.
Answer : True

Match The Column:-

Answer : (I) - (e) (Ii) - (d) (Iii) - (a) (Iv) - (b) (v) - (c)

ACTIVITY- 

Question. Name any two organic contaminants present in drain water.
Answer : Human and animal waste, fruit and vegetable waste, oils, pesticides etc.

Question. What is the difference in colour of contaminated and clean water?
Answer : Clean water is clear and transparent but contaminated water is grey or black in colour.

ACTIVITY-

Question. Name any two organisms living in and around an open drain.
Answer : Flies and mosquitoes.

Question. Why are manholes built in sewage route?
Answer : To check any problem in sewage route.

ACTIVITY- 

Question. What was removed by the sand filter?
Answer : Solid impurities.

Question. What change do you notice in the appearance of liquid after aeration?
Answer : Liquid becomes dirty after aeration

Very Short Answer Type Questions.

Question. What is sewage?
Answer : Sewage is wastewater that contains dissolved and suspended sold impurities.

Question. What is septic tank?
Answer : A septic tank is small sewage treatment system having anaerobic bacterial environment to decompose the waste matter.

Question. Why is sludge?
Answer : Sludge is the solid material that settles at the bottom of water clarifier.

Question. What is wastewater treatment plant?
Answer : Wastewater treatment plant is a system used to remove impurities from sewage and proper treatment of impurities and clarified water.

Question. What is clarified water?
Answer : Water free from impurities (contaminants) is known as clarified water.

Short Answer Type Questions.

Question. Why oil and fats should not be thrown in the drain? Comment.
Answer : Oils and fats should not be released in drain, because they can harden and block the pipes. In an open drain, the fats clog the soil pores, reducing its effectiveness in filtering water.

Question. What are the alternative arrangements for sewage disposal?
Answer : We can use septic tanks, chemical tanks and compost pits as alternative arrangements for sewage disposal.

Question. What is the function of bar screens in wastewater treatment plants?
Answer : Bar screen removes large objects like rags, sticks, cans, plastic packets and napkins.

Question. Why is it harmful to discharge untreated sewage in water bodies?
Answer : Because untreated sewage consists of various disease-causing microorganisms and pollutants that can contaminate the soil and water resources, which may cause many diseases.

Question. “Throw litter in the dustbin only” Comment.
Answer : We should through litter (rubbish) in the dustbin. With this our surrounding will remain clean and we can easily decompose the rubbish.

Long Answer Type Questions.

Question. What steps will you take at home for efficient working of sewerage system?
Answer : (1) Do not throw oil and fats into the drain.
(2) Do not throw chemicals like paints, medicines, grease, insecticides etc. into the drain.
(3) Do not throw wastes like solid food remains, tea leaves, cotton, plastic bags etc. into the drain.
(4) Do not waste water.
(5) Use only phosphate free soaps and detergents.
(6) Avoid using the toilet as a wastebasket.

Question. Write a brief note on open defecation.
Answer : A large numbers of people in our country defecate in open due to lack of sewerage facilities. Open defecation is a health hazard. It results in the spread of a number of diseases like cholera, typhoid, hepatitis-A, polio and diarrhea etc. Every year about 100,000 children die in India from diseases caused by fecal contamination. So this practice should be stopped by providing proper facilities to every citizen