Ncert solutions science class 7 Solutions for Chapter 18 wastewater story

Drains get blocked by cooking oil and ________.

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

Water polluted by various human activities causes a number of water borne diseases. Which of the following is not a water borne disease?

Which of the following is/are products of wastewater treatment?

Dried ____________ is used as manure.

Cleaning of water is a process of removing ___________.

Wastewater released by houses is called ___________.

Fill in the blanks:

(a) Cleaning of water is a process of removing ____________.

(b) Wastewater released by houses is called ____________.

(c) Dried ____________ is used as manure.

(d) Drains get blocked by ____________ and ____________.

Q1) Fill in the blanks:

(a) Cleaning of water is a process of removing ________\__.

(b) Wastewater released by houses is called _______\__.

(c) Dried _______ is used as manure.

(d) Drains get blocked by ______ and _____\__.

Q2) What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.

What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.

Q3) Why should oils and fats be not released in the drain? Explain.

Q4) Describe the steps involved in getting clarified water from wastewater.

Describe the steps involved in getting clarified water from wastewater.

Why should oils and fats be not released in the drain? Explain.

What is sludge? Explain how it is treated.

Q5) What is sludge? Explain how it is treated.

Q6) Untreated human excreta is a health hazard. Explain.

Untreated human excreta is a health hazard. Explain

Name two chemicals used to disinfect water

Q7) Name two chemicals used to disinfect water.

Explain the function of bar screens in a wastewater treatment plant.

Q8) Explain the function of bar screens in a wastewater treatment plant.

Q9) Explain the relationship between sanitation and disease.

Explain the relationship between sanitation and disease.

Q10) Outline your role as an active citizen in relation to sanitation.

Outline your role as an active citizen in relation to sanitation.

Here is a crossword puzzle: Good luck!

Across

3. Liquid waste products

4. Solid waste extracted in sewage treatment

6. A word related to hygiene

8. Waste matter discharged from human body

Down

1. Used water

2. A pipe carrying sewage

5. Micro-organisms which causes cholera

7. A chemical to disinfect water

Q11) Here is a crossword puzzle: Good luck!

Across

3. Liquid waste products

4. Solid waste extracted in sewage treatment

5. A word related to hygiene

6. The waste matter discharged from the human body

Down

1. Used water

2. A pipe carrying sewage

3. Micro-organisms which causes cholera

4. A chemical to disinfect water

Q12) 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 of 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

Study the following statements about ozone:

(a) It is essential for 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