Q1Multiple choice
Which of the following is waste water?
- (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.
Show answer
(d) Water coming out of a laundry.
Chapter 18 – Wastewater Story
Class 7 Science · 27 questions · 27 with answers
Questions
Q2Multiple choice
Sewage is mainly a
- (a)liquid waste.
- (b)solid waste.
- (c)gaseous waste.
- (d)mixture of solid and gas.
Show answer
(a) liquid waste.
Q3Multiple choice
Which of the following is/are products of wastewater treatment?
- (a)Biogas
- (b)Sludge
- (c)Both biogas and sludge
- (d)Aerator
Show answer
(c) Both biogas and sludge
Q4Multiple choice
Open drain system is a breeding place for which of the following.
- (a)Flies
- (b)Mosquitoes
- (c)Organisms which cause diseases
- (d)All of these
Show answer
(d) All of these
Q5Multiple choice
Water polluted by various human activities causes a number of water borne diseases. Which of the following is not a water borne disease?
- (a)Cholera
- (b)Typhoid
- (c)Asthma
- (d)Dysentry
Show answer
(c) Asthma
Q6Multiple choice
Pick from the following one chemical used to disinfect water.
- (a)Chlorine
- (b)Washing soda
- (c)Silica
- (d)Coal
Show answer
(a) Chlorine
Q7Multiple choice
The system of a network of pipes used for taking away wastewater from homes or public buildings to the treatment plant is known as
- (a)sewers.
- (b)sewerage.
- (c)transport system.
- (d)treatment plant.
Show answer
(b) sewerage.
Q8Multiple choice
Which of the following is a part of inorganic impurities of the sewage?
- (a)Pesticides
- (b)Urea
- (c)Phosphates
- (d)Vegetable waste
Show answer
(c) Phosphates
Q9Multiple choice
In a filtration plant water is filtered using layers of
- (a)sand and clay.
- (b)clay and fine gravel.
- (c)sand and fine gravel.
- (d)sand, fine gravel and medium gravel.
Show answer
(d) sand, fine gravel and medium gravel.
Q10Multiple choice
Which of the following is not a source of waste water?
- (a)Sewers
- (b)Homes
- (c)Industries
- (d)Hospitals
Show answer
(a) Sewers
Q11Very short answer
Why are open drains a concern?
Show answer
It is so because they create unsanitary and unhygienic conditions.
Q12Multiple choice
State whether the following statements are True or False. In case a statement is false, write the correct statement.
- (a)Sewage is a solid waste which causes water pollution and soil pollution. WASTEWATER STORY 95
- (b)Used water is wastewater.
- (c)Wastewater could be reused.
- (d)Where underground sewerage systems and refuse disposal systems are not available, the high cost on-site sanitation system can be adopted.
Show answer
(a) Sewage is a solid waste which causes water pollution and soil pollution. WASTEWATER STORY 95
Hint: Hint: Write ‘liquid’ in place of ‘solid’). (b) True (c) True (d) False (Hint: Write ‘low’ in place of ‘high’).
Q13Very short answer
How are open drains harmful for human health?
Show answer
In the unhygienic conditions of open drains, flies, mosquitoes, and other insects breed and spread a number of diseases. SHORT ANSWER QUESTIONS
Q14Short answer
Name two inorganic impurities present in sewage.
Show answer
Nitrates, Phosphates, Metals (any two).
Q15Short answer
Animal waste, oil and urea are some of the organic impurities present in sewage. Name two more organic impurities present in sewage.
Show answer
Pesticides, herbicides, fruits and vegetable waste (any two).
Q16Short answer
Name two alternative arrangements for sewage disposal where there is no sewerage system.
Show answer
(i) Septic tanks (ii) Composting pits
Q17Short answer
A man travelling in a train threw an empty packet of food on the platfrom. Do you think this is a proper waste disposal method? Elaborate.
Show answer
No, one must always put the waste in a nearby dustbin or carry it until a proper place to dispose it of is found. Waste, not properly disposed may go into the drains and choke them. It also makes public places dirty and unhygienic.
Q18Multiple choice
Why should we not throw
- (a)used tea leaves into sink?
- (b)cooking oil and fats down the drain?
Show answer
(a) used tea leaves into sink?
(b) cooking oil and fats down the drain?
Q19Match the following
Match the items of Column I with the items of Column II with reference to sewage.
Show answer
(a) (ii); (b) (iv); (c) (i); (d) (iii)
Q20Multiple choice
Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Arrange them in their correct sequence.
- (a)Sludge is scraped out and skimmer removes the floating grease.
- (b)Water is made to settle in a large tank with a slope in the middle.
- (c)Large objects like plastic bags are removed by passing wastewater through bar screens.
- (d)Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater. (e) Wastewater enters a grit and sand removal tank.
Show answer
(c) Large objects like plastic bags are removed by passing wastewater through bar screens.
(d) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater. (e) Wastewater enters a grit and sand removal tank.
(b) Water is made to settle in a large tank with a slope in the middle.
(a) Sludge is scraped out and skimmer removes the floating grease.
Q21Multiple choice
Three statements are provided here which define the terms –
- (a)sludge
- (b)sewage and
- (c)wastewater. Pick out the correct definition for each of these terms. (a) The settled solids that are removed in wastewater treatment with a scraper. (b) Water from kitchen used for washing dishes. (c) Wastewater released from homes, industries, hospitals and other public buildings.
Show answer
(a) sludge
(b) sewage and
(c) wastewater. Pick out the correct definition for each of these terms. (a) The settled solids that are removed in wastewater treatment with a scraper. (b) Water from kitchen used for washing dishes. (c) Wastewater released from homes, industries, hospitals and other public buildings.
Q22Multiple choice
A mixture (x) in water contains suspended solids, organic impurities, inorganic impurities
- (a), nutrients
- (b), disease causing bacteria and other microbes. Give names for (x), (a) and (b)?
Show answer
(a) , nutrients
(b) , disease causing bacteria and other microbes. Give names for (x), (a) and (b)?
Q23Long answer
What are the different types of inorganic and organic impurities generally present in sewage?
Show answer
(i) Inorganic impurities – nitrates, phosphates and metals. (ii) Organic impurities – fruit and vegetable wastes, oil, urea, human faeces, animal waste, pesticides and herbicides.
Q24Long answer
The terms sewage, sewers and sewerage are interlinked with each other. Can you explain, how? WASTEWATER STORY 97
Show answer
Hint: (i) Sewage – mixture of wastewater coming out of homes and other places. (ii) Sewers – pipes which carry sewage. (iii) Sewerage – network of sewage carrying pipes.
Q25Fill in the blanks
Fill in the blanks in the following statements using words given in the box. air, handpumps, cholera, water, large, ground A very _________ number of our people defecate in the open. It may cause _________ pollution and soil pollution. Both the surface water and _________ water get polluted. _________ water is the source for wells, tubewells and _________. Thus it becomes the most common route for _________ borne diseases like _________, dysentery, etc.
Show answer
large, water, ground, ground, handpumps, water, cholera.
Q26Long answer
Describe various steps of cleaning wastewater in a wastewater treatment plant.
Show answer
Hint: See pages 223 and 224 of Chapter 18 of NCERT Science textbook for Class VII.
Q27Long answer
Think and suggest some ways to minimise waste and pollutants at their source, taking your home as an example.
Show answer
Hint: Some points are given here, you can add more. (i) Do not throw used tea leaves, solid food remains, etc. in the drain. Throw them in the dustbin. (ii) Chemicals like medicines, paints, insecticides, etc. should not be thrown in the drain, as they increase the pollution load of the sewage.