KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story

Students can Download Science Chapter 18 Wastewater Story Questions and Answers, Notes Pdf, KSEEB Solutions for Class 7 Science helps you to revise the complete Karnataka State Board Syllabus and to clear all their doubts, score well in final exams.

Karnataka State Syllabus Class 7 Science Chapter 18 Wastewater Story

Class 7 Science Wastewater Story Textbook Exercise Questions and Answers

Question 1.
Fill in the blanks.

  1. Cleaning of water is a process of removing _____________.
  2. Waste water released by houses is called _____________.
  3. Dried is used as manure _____________.
  4. Drains get blocked by and _____________.

Answer:

  1. pollutants
  2. sewage
  3. sludge
  4. cooking oil, fats.

KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story

Question 2.
What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.
Answer:
Sewage is a liquid waste which has water as its largest component along with various types of impurities like wastewater from houses, offices, factories, hospitals, etc. is called sewage. It has a complex and inorganic impurity, nutrients, saprotrophic and disease-causing bacteria, and other microbes.

Discharging untreated sewage into rivers or seas will pollute the water resources. Contaminated water is dangerous for aquatic plants and animals. It also spread many diseases like cholera, typhoid, polio meningitis, malaria, dengue, etc.

Question 3.
Why should oils and fats be not released in the drain? Explain.
Answer:
Oils and fats should not be released in the drain because they can become harder and block the pipes. If they clog the soil pores, reducing its effectiveness in filtering water.

KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story

Question 4.
Describe the steps involved in getting clarified water from wastewater.
Answer:
The steps involved in getting clarified water from wastewater are as follows :

  1. Use an aerator to bubble air through the wastewater. A mechanical stirrer or a mixer can also be used in the place of the aerator. This helps in reducing the bad odour of the Wastewater.
  2. Then, the water is filtered through the layers of sand, fine gravel, and medium gravel, filtration makes the wastewater clean from various-types of pollutants. The water is filtered continuously until it becomes clear.
  3. Then any disinfectant such as chlorine tablet is added, to the filtrate and stirred to obtain completely clear water.

KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story

Question 5.
What is sludge? Explain how it is treated.
Answer:
Solids like feces settle down during wastewater treatment are called sludge. This sludge is removed using a scraper and then transferred to a tank where it is decomposed by the anaerobic bacteria to produce biogas. The biogas so produced can be used as fuel or can be used to produce electricity.

Question 6.
Untreated human excreta is a health hazard. Explain.
Answer:
Untreated human excreta is a health hazard. It may cause water pollution and soil pollution. It pollutes groundwater also. If this contaminated water is used for drinking, then it may cause diseases like cholera, typhoid, polio, meningitis, hepatitis, and dysentery.

Question 7.
Name two chemicals used to disinfect water.
Answer:
The two chemicals used to disinfect water are chlorine and ozone.

KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story

Question 8.
Explain the function of bar screens in a wastewater treatment plant.
Answer:
The bar screens in a wastewater treatment plant are used to remove large objects like rags, sticks, cans, plastic packets napkins, etc. present in wastewater.

Question 9.
Explain the relationship between sanitation and diseases.
Answer:
A large number of diseases is caused due to poor sanitation and contaminated drinking water. Poor sanitation leads to the growth of harmful microbes, flies and mosquitoes which are the source of spreading many diseases like cholera, typhoid, polio, meningitis, hepatities, and dysentery.

KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story

Question 10.
Outline your role as an active citizen in relation to sanitation.
Answer:
An active citizen has many responsibilities in relation to sanitation. The waste should be disposed of properly. We should not scatter litter anywhere. We should carry the litter home and throw it in the dustbin if there is no dustbin insight. The sewerage system in our houses should be maintained properly. We should not defecate in the open. If we notice any leakage in the sewerage system, then we should report it to the municipality.

Question 11.
Here is a crossword puzzle: Good luck!
KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story 1
Across
3. Liquid waste products.
4. Solid waste extracted in sewage treatment.
6. A word related to hygiene.
8. Waste matter discharged from the human body.
Down
1. Used water.
2. A pipe carrying sewage.
5. Micro-organisms which causes cholera;
7. A chemical to disinfect water.
Answer:
KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story 2

KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story

Question 12.
Study the following statements about ozone:
(a) It is essential for the breathing of living organisms.
(b) It is used to disinfect water.
(c) It absorbs ultraviolet rays.
(d) Its proportion in air is about 3%. Which of these statements are correct?
(i) (a), (b) and (c)
(ii) (b) and (c)
(iii) (a) and (d)
(iv) All four
Answer:
(ii) (b) and (c).

KSEEB Solutions for Class 7 Science Chapter 18 Wastewater Story

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