Page 162 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

5. Open drain system is a breeding place for which of the following?

(a) Flies (b) Organisms that cause diseases
(c) Mosquitoes (d) All of the above

Ans: (d)
B. Fill in the blanks.

1. Dried sludge is used as ...................... .

Ans: manure
2. Toilets in aeroplanes are ...................... toilets.

Ans: vacuum

3. The full form of WWTP is ...................... .
Ans: Waste Water Treatment Plant

4. Untreated human excreta is a ...................... hazard.
Ans: health

5. Sewage contains organic and ...................... impurities.
Ans: inorganic

6. The current vacuum toilet system used in aeroplanes was designed by ......................

in 1974.
Ans: James Kemper

C. State whether the following statements are true (T) or false (F).
1. Sewage contains bacteria that causes diseases.

2. Used water is wastewater.
3. Microorganisms are present in the domestic wastewater also.

4. Urea is an inorganic impurity present in sewage.

5. Wastewater can be reused.
6. Sewage from houses should first be treated at sewage treatment plants before it is

allowed to flow into water bodies.
7. Throwing oil in drains is the best way to discard grease.

Ans: 1. (T) 2. (T) 3. (T) 4. (T) 5. (T) 6. (T) 7. (F)
D. Very short-answer questions.

1. Name two inorganic impurities present in sewage.

Ans: Phosphates & Nitrates
2. Which day is celebrated as World Water Day?

Ans: 22nd March
3. Name the bacteria that proliferate in the presence of air.

Ans: Aerobic bacteria

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