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Important Questions Test: Waste Water Story - Class 7 MCQ


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15 Questions MCQ Test - Important Questions Test: Waste Water Story

Important Questions Test: Waste Water Story for Class 7 2024 is part of Class 7 preparation. The Important Questions Test: Waste Water Story questions and answers have been prepared according to the Class 7 exam syllabus.The Important Questions Test: Waste Water Story MCQs are made for Class 7 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Important Questions Test: Waste Water Story below.
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Important Questions Test: Waste Water Story - Question 1

Out of the following, select those that would help to reduce water pollution.

(i) use of sewers for removal of urban waste
(ii) use of unleaded petrol in cars
(iii) spraying of pesticides on plants
(iv) We should not excreate in open.

Detailed Solution for Important Questions Test: Waste Water Story - Question 1

because using pesticides on plants is no way useful to reduce water pollution and use of unleaded petrol in cars is related to air pollution. 

So, statement (1) and (4) is correct.

Important Questions Test: Waste Water Story - Question 2

The international decade for action on "water for life" by United Nations General Assembly was declared on

Detailed Solution for Important Questions Test: Waste Water Story - Question 2

It was declared in 22 March, 2005.

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Important Questions Test: Waste Water Story - Question 3

Which of the following group is against the plantation of Eucalyptus trees?

Detailed Solution for Important Questions Test: Waste Water Story - Question 3

Eucalyptus is an efficient biomass producer, it can produce more biomass than many other tree species. Growing Eucalyptus in low rainfall areas may cause adverse environmental impacts due to competition for water with other species.

Important Questions Test: Waste Water Story - Question 4

The impurities present in sewage may consist of

Detailed Solution for Important Questions Test: Waste Water Story - Question 4

The impurities present in sewage water may consists of organic or inorganic substances .

Important Questions Test: Waste Water Story - Question 5

The sludge waste originates from

Detailed Solution for Important Questions Test: Waste Water Story - Question 5

Waste that originates from kitchen is known as sludge.

Important Questions Test: Waste Water Story - Question 6

Which of the following are removed by use of A skimmer in WWTP?

Detailed Solution for Important Questions Test: Waste Water Story - Question 6

A skimming tank is a chamber so arranged that the floating matter like oil, fat, grease etc., rise and remain on the surface of the waste water.

Important Questions Test: Waste Water Story - Question 7
Cleaning of water is a process of removing _______.
Detailed Solution for Important Questions Test: Waste Water Story - Question 7
Cleaning of water involves removing contaminants, which include pollutants, chemicals, and other harmful substances that can affect water quality and safety.
Important Questions Test: Waste Water Story - Question 8
What is sewage? why it is harmful to discharge untreated sewage into rivers or seas.
Detailed Solution for Important Questions Test: Waste Water Story - Question 8
Sewage is wastewater from homes, including toilets, kitchens, and laundries. Discharging untreated sewage into rivers or seas introduces harmful microorganisms and pollutants, leading to water contamination and disease outbreaks.
Important Questions Test: Waste Water Story - Question 9
Why should oils and fats not be released in the drain? Explain.
Detailed Solution for Important Questions Test: Waste Water Story - Question 9
Oils and fats can solidify in pipes and drains, leading to blockages and clogs. These substances do not easily break down and can cause severe plumbing issues.
Important Questions Test: Waste Water Story - Question 10

What is sludge? how it is treated.

Detailed Solution for Important Questions Test: Waste Water Story - Question 10

Sludge is a semi-solid byproduct that is produced during wastewater treatment processes. It is composed of both organic and inorganic materials that settle out during sedimentation, often containing a mixture of water, microorganisms, and solid waste materials.

Treatment of Sludge:

The most common method for treating sludge is anaerobic digestion. Here’s how the process works:

  1. Anaerobic Digestion:
    • In this process, sludge is placed in a sealed container known as an anaerobic digester, where bacteria break down the organic material in the absence of oxygen.
    • The digestion process produces biogas (methane and carbon dioxide) as a byproduct, which can be captured and used for energy generation.
    • Anaerobic digestion reduces the volume of sludge, stabilizes it, and reduces odors. The end product is a digested sludge, which can sometimes be further treated for use as fertilizer.

This method is preferred because it reduces the volume of waste, produces useful byproducts like biogas, and minimizes environmental impacts.

Other Methods of Treatment:

  • Dewatering: Sludge is often dewatered to reduce its water content, making it easier to handle and transport.
  • Incineration: Sometimes, dried sludge is burned to reduce its volume, though this can be energy-intensive and release pollutants if not controlled properly.
  • Composting: In some cases, treated sludge can be composted to be used as a soil conditioner.
Important Questions Test: Waste Water Story - Question 11
Name two chemicals used to disinfect water.
Detailed Solution for Important Questions Test: Waste Water Story - Question 11
Chlorine and ozone are commonly used to disinfect water. They effectively kill harmful microorganisms, making the water safe for consumption. Chlorine is widely used in water treatment plants, while ozone is known for its strong oxidizing properties.
Important Questions Test: Waste Water Story - Question 12
What is the role of chlorination in water treatment?
Detailed Solution for Important Questions Test: Waste Water Story - Question 12
Chlorination involves adding chlorine to water to kill harmful microorganisms, making the water safe to drink. It is a crucial step in ensuring water quality and preventing waterborne diseases.
Important Questions Test: Waste Water Story - Question 13

What is the function of sedimentation in wastewater treatment?

Detailed Solution for Important Questions Test: Waste Water Story - Question 13

The function of sedimentation in wastewater treatment is primarily

Settling Suspended Particles: Sedimentation allows suspended particles, such as silt, sand, and organic matter, to settle at the bottom of a tank due to gravity and then decant can be taken out which will be free of these impurities. 

Important Questions Test: Waste Water Story - Question 14
What is the primary purpose of using a scraper in a wastewater treatment plant?
Detailed Solution for Important Questions Test: Waste Water Story - Question 14
A scraper is used to remove sludge that settles at the bottom of treatment tanks. This sludge is then transferred for further treatment, such as anaerobic digestion, to produce biogas and manure.
Important Questions Test: Waste Water Story - Question 15
What is one of the key benefits of using biogas produced from sludge?
Detailed Solution for Important Questions Test: Waste Water Story - Question 15
Biogas produced from sludge is a renewable source of energy. It can be used for heating, cooking, and generating electricity, providing a sustainable energy option and reducing dependence on fossil fuels.
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