Waste water Story WS 01 - Worksheets

 CBSE Worksheet-01

Class – VII Science (Waste-water Story)

  1. Liquid waste from houses is called
    1. Sewage
    2. Sludge
    3. Smog
    4. Effluent
  2. Biodegradable waste
    1. Decomposes in nature by microbes
    2. Does not decompose
    3. Enters the food chains then causes bio magnification
    4. Accumulates in environment
  3. Polythene and plastics
    1. Degrade in the environment very easily
    2. Are not harmful
    3. Do not generate any bad odour
    4. Are non-biodegradable and very harmful
  4. Which of the following is non-biodegradable waste?
    1. Vegetable and fruit peels.
    2. Plants and animals excreta
    3. Plastic
    4. Cotton cloths
  5. Match the following
    Column AColumn B
    a. Polythenei. Waste water from homes and industries
    b. Fruits peelii. Chlorination
    c. Sewer systemiii. Biodegradable
    d. Sewageiv. Network of drainage pipe to carry sewage
    e. Disinfectionv. Non-biodegradable
  6. Fill in the blanks with suitable words
    1. After treatment the sewage is discharged into a ________.
    2. The ________ system transport the sewage from homes to treatment plant.
    3. Last stage in treatment of sewage is ________.
    4. Open drains cause ________ conditions.
    5. Solid parts of sewage can be used as ________.
  7. What is meant by sewage? What does it mainly consists of?
  8. Mention some importance of drainage system.
  9. Write difference between biodegradable and non-biodegradable wastes.
  10. Solve the cross word puzzle.
    2. Useless things produced.
    4. Chemicals used for killing germs.
    1. Waste water from homes and industries.
    3. Disease causing microorganisms.
    5. Non-biodegradable solid waste
  11. What are different methods to make water potable (fit for drinking)?

CBSE Worksheet-01
Class – VII Science (Waste-water Story)
Answer key

1. a
2. a
3. d
4. c
5. (a) – (v), (b) – (iii), (c) – (iv), (d) – (i), (e) – (iv).
6. (a) Water bodies (b) sewer system (c) chlorination (d) unhygienic (e) fertilizers.
7. Sewage is the waste water from homes and industries. It consists of human excreta, dirt, and food particles etc.
8. Drainage system is an absolute necessity for safe disposal of sewage. In absence of an efficient system of sewage the sanitation of a place may suffer. It may cause water borne disease.
9. Biodegradable wastes are organic wastes which are decomposed by bacteria and other microorganisms into simpler components. Non biodegradable are mostly inorganic and can not be converted into simpler forms.

11. We use different methods in our homes to make water potable. Water obtained from the source is filtered before use. Those who depend on wells for the supply of water pot a few crystals of potassium permanganate into the well. Bleaching powder chlorine tablets are also used to make water fit for drinking. Now-a-days machines are available for water purification in which water is passed through carbon filter, ultra-violet ray or through Reverse Osmosis process.