Check the below Online Education NCERT MCQ Questions for Wastewater Story Class 7 Extra Questions and Answers Science Chapter 18 Pdf free download. https://ncertmcq.com/extra-questions-for-class-7-science/
Online Education for Class 7 Science Chapter 18 Extra Questions and Answers Wastewater Story
Wastewater Story Class 7 Extra Questions With Answers Question 1.
Which day is celebrated as the World Water Day?
Answer:
22nd March.
Waste Water Story Class 7 Extra Questions Question 2.
What do you understand by ‘waste-water?
Answer:
Rich in lather, mixed with oil, black-brown water that goes down the drains from sinks, showers, toilets, laundries is dirty. It is called wastewater.
Class 7 Science Chapter 18 Extra Questions Question 3.
Which period has been proclaimed as the International decade for action on “Water for life”?
Answer:
United Nations proclaimed the period 2005-2015 as the International Decade for action on “Water for life”.
Ch 18 Science Class 7 Extra Questions Question 4.
What do you mean by cleaning of water?
Answer:
Cleaning of water is a process of removing pollutants before it enters a water body or is reused.
Waste Water Story Class 7 Questions And Answers Question 5.
What is sewage treatment?
Answer:
The process of wastewater treatment is commonly known as “Sewage Treatment”.
Wastewater Story Class 7 Worksheet With Answers Question 6.
Why is the speed of incoming wastewater decreased in the grit and sand removal tank?
Answer:
The speed of the incoming wastewater in the grit and sand removal tank is decreased to allow sand, grit and pebbles to settle down.
Ncert Solutions For Class 7 Science Chapter 18 Extra Questions Question 7.
Why should we plant eucalyptus along sewage ponds?
Answer:
Eucalyptus absorb all surplus wastewater rapidly and release pure water vapour into the atmosphere.
Wastewater Story Class 7 Questions With Answers Question 8.
How do sand, grit and pebbles settle down in the grit and sand removal tank?
Answer:
Jn grit amps and removal tank, the speed of the incoming wastewater is decreased to allow sand, grit and pebbles to settle down.
Extra Questions For Class 7 Science Chapter 18 Question 9.
Why is air pumped into clarified water?
Answer:
Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water.
Class 7 Science Ch 18 Extra Questions Question 10.
How is dry sludge used?
Answer:
Dried sludge is used as manure, returning organic matter and nutrients to the soil.
Ncert Class 7 Science Chapter 18 Extra Questions Question 11.
What is done to improve sanitation?
Answer:
To improve sanitation, low-cost onsite sewage disposal systems are being encouraged. Examples are septic tanks, chemical toilets, composting pits. Septic tanks are suitable for places where there is no sewerage system, for hospitals, isolated buildings or a cluster of 4 to 5 houses.
Extra Questions On Waste Water Story Class 7 Question 12.
What is vermi-process toilet?
Answer:
A vermi-processing toilet is a design of a toilet in which humans excreta is treated by earthworms. It has been found to be a novel, low water-use toilet for safe processing of human waste. In the vermi processing toilet, the human excreta is completely converted to vermi cakes- a resource is much needed for soil.
Extra Questions For Class 7 Science Wastewater Story Question 13.
What is done with the sludge produced in Wastewater Treatment Plant? Is it used to us? If yes, how?
Answer:
The sludge produced in Wastewater Treatment Plant is transferred to a separate tank when it is decomposed by the anaerobic bacteria. The biogas produced in the process can be used as fuel or can be used to produce electricity.
Waste Water Story Class 7 Extra Questions And Answers Question 14.
Why is air pumped into the clarified water? What is the role of aerobic bacteria in cleaning of water?
Answer:
Air is pumped into the clarified water to help aerobic bacteria to grow. These bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water.
Class 7 Wastewater Story Extra Questions Question 15.
Suggest some better housekeeping practices.
Answer:
- Cooking oil and fats should not be thrown down the drain. They can harden and block the pipes. In an open drain, the fats clog the soil pores reducing its effectiveness in filtering water. Oil and fats should be thrown in the dustbin.
- Chemicals like paints, solvents, insecticides, motor oil, medicines may kill microbes that help to purify water. So, they should not be thrown in the drain.
- Used tea leaves, solid food remains, soft toys, cotton, sanitary towels, etc. should also be thrown in the dustbin. These wastes choke the drains. They do not allow free flow of oxygen. This hampers the degradation process.
Question 16.
What is the composition of sewage?
Answer:
Sewage is a complex mixture containing suspended solids, organic and inorganic impurities, nutrients, saprotrophic and disease-causing bacteria and other microbes.
Organic impurities-Human faeces, animal waste, oil, urea (urine), pesticides, herbicides, fruit and vegetable waste, etc. Inorganic impurities-Nitrates, Phosphates, metals. Nutrients-Phosphorus and Nitrogen. Bacteria-Such as which causes cholera and typhoid. Other microbes-Such as amoeba which causes dysentery.
Question 17.
Outline your role as an active citizen in relation to sanitation.
Answer:
We all have a role to play in keeping our environment clean and healthy. We must realise our responsibility in maintaining the water sources in a healthy state. Adopting good sanitation practices should be our way of life. As an agent of change, our individual initiative will make a great diffèrence. We can influence others with our energy, ideas and optimism. A lot can be done if people work together. There is great power in collective action.
Question 18.
Explain the relationship between sanitation and disease.
Answer:
Untreated human excreta is a health hazard. Improper sanitation may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for wells, tube wells, springs and many rivers. Thus, it becomes the most common route for water-borne diseases. They include cholera, typhoid, polio, meningitis hepatitis and dysentery. That is why proper sanitation is must to avoid some of the deadliest diseases.
Question 19.
Untreated human excreta is a health hazard. Explain.
Answer:
Untreated human excreta is a health hazard. It may cause water pollution and soil pollution. Both the surface water and groundwater get polluted. Groundwater is a source of water for wells, tube wells, springs and many rivers. Thus, it becomes the most common route for water-borne diseases They include cholera, typhoid, polio, meningitis, hepatitis and dysentery.
Question 20.
What is sludge? Explain how it is treated.
Answer:
During physical treatment, solids like faeces settle at the bottom of the large tank. This is called sludge. Treatment of sludge (basically biological treatment)
- Sludge are first removed from the bottom using a scraper.
- Sludge is then transferred to a separate tank. where it is decomposed by the anaerobic bacteria.
The biogas produced in the process can be used as fuel.
Question 21.
Describe the steps involved in getting clarified water from wastewater.
Answer:
Treatment of wastewater involves physical, chemical, and biological processes, which remove physical, chemical and biological matter that contaminates the water.
Physical:
- Wastewater is passed through bar screens. Large objects like rags, sticks, cans, plastic packets, napkins are removed.
- Water goes to a grit and sand removal tank. The speed of the incoming wastewater is, decreased to allow sand, grit and pebbles to settle down.
Biological:
The water is then allowed to settle large tank which is sloped upwards the middle. Solids like faeces sett the bottom and, a removed with a scraper.’ this is the sludge. skimmer removes the floatable solids like and grease. Water so cleared is called clarified water. The sludge is transferred to a separate tank where it is decomposed by the anaerobic bacteria.
Air is pumped into the clarified water to help aerobic bacteria to grow. Bacteria consume human waste, food waste, soaps and other unwanted matter still remaining in clarified water.
After several hours, the suspended microbes settle at the bottom of the tank as activated sludge. The water is then removed from ‘the top. Chemical: Sometimes it may be necessary to disinfect water with chemicals like chlorine and ozone before releasing it into the distribution system.
Question 22.
Why should oils and fats be not released in the drain? Explain.
Answer:
Oil does not mix with water. Being lighter, oil floats on water. This prevents mixing of water and air. This reduces oxygen supply for aquatic plants and animals. Along with, in an open drain, the fats clog the soil pores reducing its effectiveness in filtering water.
Question 23.
What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.
Answer:
Sewage is wastewater released by homes, industries, hospitals, offices and other users. It also includes rainwater that has run down the streets during a storm or heavy rain. The water that washes off roads and rooftops carries harmful substances with it. Sewage is a liquid waste. Most of it is water, which has dissolved and suspended impurities which are called contaminants. That is why it is harmful to discharge untreated sewage into rivers or seas.
Question 24.
Why should oils and fats be not released in the drain? Explain.
Answer:
Oil does not mix with water. Being lighter, oil floats on water. This prevents mixing of water and air. This reduces oxygen supply for aquatic plants and animals. Along with, in an open drain, the fats clog the soil pores reducing its effectiveness in filtering water.
Multiple Choice Questions
1. Which of the following activities requires clean water as a must?
(i) Bathing
(ii) Cleaning utensils
(iii) Drinking
(iv) Washing clothes.
Answer:
(iii) Drinking.
2. Which of the following is not a means of exploiting water resources?
(i) Pollution
(ii) Industrial drainage
(iii) Drinking
(iv) Misarrangement
Answer:
(iii) Drinking.
3. Find the odd one out.
(i) Sewage water – Kitchen
(ii) Foul waste – Toilets
(iii) Trade waste – Industrial and commercial organisations
(iv) Drinking water – Ocean
Answer:
(iv) Drinking water – Ocean.
4. Which of the following statements is correct?
(i) Sewage is a source clean water.
(ii) Sewage does not contain any waste product.
(iii) Sewage comes out of industries.
(iv) Sewage is a mixture of wastewater from home, office, industries etc.
Answer:
(iv) Sewage is a mixture of wastewater from home, office, industries etc.
5. For cleaning wastewater at home, the sequence of processes is :
(i) aeration, filiation, chlorination
(ii) filtration, aeration, chlorination
(iii) filtration, chlorination, aeration
(iv) chlorination, filtration, aeration.
Answer:
(i) aeration, filiation, chlorination.
6. Aeration is a process to remove :
(i) undesired substances
(ii) foul smell
(iii) bacteria
(iv) chlorine.
Answer:
(ii) foul smell.
7. Chlorination is a process for :
(i) removing foul smell
(ii) disinfection
(iii) removing viruses
(iv) removing undesirable substances
Answer:
(ii) disinfection.
Keywords:
→ Aeration: Mixing with air.
→ Aerobic bacteria: Bacteria that need oxygen.
→ Anaerobic bacteria: Bacteria that do not need oxygen.
→ Biogas: Gas produced by the decomposition of organic matter.
→ Contaminant: Dissolved and suspended impurities in water are called contaminants.
→ Sanitation: Toilet system.
→ Sewage: Sewage is wastewater released by choices, industries, hospitals, offices and other users. It also includes rainwater that has run down the street during a storm or heavy rain.
→ Sewer: Pipes to carry sewages is called sewer.
→ Sewerage: Network of sewers is called sewerage.
→ Sludge These are Solid wastes like faeces that settle down at the bottom in the tank and are removed with a scraper.
→ Wastewater: The dirty water which is left after the different purposeful works like washing, bathing etc. is termed as wastewater.