NCERT Class VII Science Solutions: Chapter 18-Wastewater Story Part 2 (For CBSE, ICSE, IAS, NET, NRA 2023)
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Question 8:
Which of the following is a part of inorganic impurities of the sewage?
- Pesticides
- Orca
- Phosphates
- Vegetable waste
Answer: C
Question 9:
In a filtration plant water is filtered using layers of
- Sand and clay.
- Clay and fine gravel.
- Sand and fine gravel.
- Sand, fine gravel and medium gravel.
Answer: D
Question 10:
Which of the following is not a source of waste water?
- Sewers
- Homes
- Industries
- Hospitals
Answer: A
VERY SHORT ANSWER QUESTIONS
Question 11:
Why are open drains a concern?
Answer:
It is so because they create unsanitary and unhygienic conditions.
Question 12:
State whether the following statements are true or false. In case a statement is false, write the correct statement.
- Sewage is a solid waste which causes water pollution and soil pollution.
- Used water is wastewater.
- Wastewater could be reused.
- Where underground sewerage systems and refuse disposal systems are not available, the high cost on-site sanitation system can be adopted.
Answer:
- Sewage is a solid waste which causes water pollution and soil pollution. (False)
(Hint: Write ‘liquid’ in place of ‘solid’ )
- Used water is wastewater. (True)
- Wastewater could be reused. (True)
- Where underground sewerage systems and refuse disposal systems are not available, the high cost on-site sanitation system can be adopted. (False)
(Hint: Write ‘low’ in place of ‘high’ )
Question 13:
How are open drains harmful for human health?
Answer:
Open drain system creates the most unhygienic and unsanitary condition in its neighborhood. Open dirty water drains are breeding places for flies, mosquitoes and other diseases causing organism.