INTERNATIONAL INDIAN SCHOOL, AL - JUBAIL
CLASS: VII SUBJECT: SCIENCE April,2024
CHAPTER # WASTEWATER STORY
I. Chose the correct option:
1. The process of removing pollutants in water before it enters a water body is
called
(a) cleaning of water
(b) refining
(c) filtering of water
(d) none of these
Answer: (a) cleaning of water
2. Which of the following is a part of inorganic impurities of the sewage?
(a) Pesticides
(b) Urea
(c) Phosphates
(d) Vegetable waste
Answer: (c) Phosphates
3. The equipment that removes floatable particles from wastewater is
(a) sludge
(b) bar screen
(c) skimmer
(d) sedimentation tank
Answer: (c) skimmer
4. The tree that helps in wastewater treatment by absorbing water greatly and
releasing pure water in environment through transpiration is
(a) peepal tree
(b) banyan tree
(c) eucalyptus tree
(d) banana tree
Answer: (c) eucalyptus tree
5. The aerobic bacteria can be grown in clarified water by
a) Filtration
b) Sewage
c) Aeration
d) Sedimentation
Answer: (c) Aeration
6. Solid waste extracted during sewage treatmet is known as
(a) sewage
(b) sludge
(c) biogas
(d) contaminants
Answer: (b) sludge
7. Cooking oil and fats should not be thrown down the drain because
(a) They flow through the drain freely
(b) It allows the particles to get filtered
(c) They hardened and blocked the pipe
(d) They break the pipe
Answer: (c) They hardened and blocked the pipe
8. WWTP stands for
a) Waste Water Treatment plant
b) Waste water Therapy plant
c) Waste Water Tremendous plant
d) Waste water Travel plant
Answer: (a) Waste Water Treatment Plant
9.Period 2005-2015 is being celebrated as the international decade for action on
a) Water for life
b) Education for all
c)Global warming
d) Tourism
Answer: (a) Water for life
10. The network of drainage pipe to carry waste water is called
a) Sewer system
b) Water supply system
c) Drainage
d) Waste water supply
Answer:(a) Sewer system.
II. ASSERTION REASON QUESTIONS
Choose correct answer for assertion reason questions according to following
options:
a) Assertion and reason are true and reason is the correct explanation for
assertion.
b) Assertion and reason are true and reason is not the correct explanation for
assertion.
c) Assertion is true but reason is false.
d) Assertion is false but reason is true.
Q1. Assertion – Untreated human excreta is a health hazard.
Reason- It may cause water pollution and soil pollution.
Ans- option A
Q2. Assertion- Vermi processing toilets are those toilets in which human excreta
is treated by bacteria.
Reason- The human excreta is completely converted into vermi cakes
Ans: option D
Q3. Assertion-The underground network of big and small pipes that carries
sewage from point of being produced to the point of disposal is known as
sewerage.
Reason-In sewerage manholes are located at every 90 to 100 meter.
Ans: option C
III. Case study questions
1. In a home or a public building generally one set of pipes brings clean water
and another set of pipes takes away wastewater. Imagine that we could see
through the ground. We would see a network of big and small pipes, forming the
sewerage.
Q1. Define sewerage.
Ans. It is like a transport system that carries sewage from the point of being
produced to the point of disposal.
Q2. What is sewage?
Ans. Sewage is a liquid waste released by homes, industries, hospitals, offices
and other users.
2. In waste water treatment plants the air is pumped into the clarified water. After
several hours the suspended microbes settle at the bottom of tank . The treated
water is discharged into the sea, a river or into the ground. Nature cleans it up
further. Sometimes it may be necessary to disinfect water with chemicals before
releasing it into the distribution system.
Q1. Name two chemicals used to disinfect water .
Ans. Chlorine and Ozone.
Q2. Why air is pumped into the clarified water?
Ans. Air is pumped into the clarified water because it helps in the growth of
bacteria.
Question and Answer
1.What is the function of bar screens in a wastewater treatment plant ?
Ans: In a wastewater treatment plant, large objects like stone, plastic bags,
cans, sticks, napkins are removed by passing the wastewater through bar
screens
2. What is sludge?
Ans: Semi-solids such as faeces that settle down during wastewater treatment
are called sludge.
Prepared by-Mrs. Ankita Singh Rawat
Verified by-Mrs. Honey Biju(coordinator GS)
