Page 164 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

5. What is sanitation?

Ans: Sanitation refers to the conditions relating to the health of people, especially the
disposal of waste and provision of clean drinking water.

6. What are the adverse effects of oil spills in water bodies?
Ans: It is harmful for marine life, such as fish and various sea animals.

The spilled oil coats the skin of the aquatic animals and makes it difficult for them to

breathe.
7. What do you mean by water pollution?

Ans: Water Pollution
When oceans, seas, rivers, lakes, ponds and underground water get contaminated,

it is known as water pollution. The change in physical, biological and chemical
properties of water due to the presence of toxic substances either dissolved or

suspended makes it unfit for consumption.

8. List the advantages of vaccum toilets.
Ans: Advantages of vacuum toilets are:

(a) They use very little water.
(b) Sewer pipes of much smaller diameter can be used.

(c) They are easy to install.
9. What is sludge?

Ans: Sludge is a thick, muddy substance left over after swage is treated. It contains water,

waste solids & microorganisms. It is often further processed for safe disposal or used
as fertilizers.

F. Long-answer questions.
1. What is a sewerage? How does it help to manage wastewater?

Ans: A sewerage is a network of sewers that carries the wastewater from the point where
it is produced to the main sewer or sewage treatment plant (the point where it is

disposed). In a sewerage system, manholes are provided at the junction of two or

more sewers. They are used for the purpose of maintenance, repair and cleaning.
Sewerage systems help manage wastewater by collecting & transporting it from

homes, businesses & other sources to treatment plants where it is treated to remove
harmful substances, bacteria & pollutants. Cleaned water is then safely released into

the environment or reused, preventing pollution of any type.
2. Untreated human excreta is a health hazard. Justify the statement.

Ans: It is because it contains pathogens, including bacteria, viruses & parasites, which can
cause serious diseases such as cholera, typhoid & hepatitis.

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