Very Short Question Answers - Waste Water Story Class 7 Notes | EduRev

Science Class 7

Class 7 : Very Short Question Answers - Waste Water Story Class 7 Notes | EduRev

The document Very Short Question Answers - Waste Water Story Class 7 Notes | EduRev is a part of the Class 7 Course Science Class 7.
All you need of Class 7 at this link: Class 7

Very Short Q & A :

Q1: What is sewage?

Ans : Waste water released by houses is called sewage.

Q2: What per cent of earth’s water is fresh?

Ans : 3 per cent.

Q3: What constitutes waste water?

Ans : It can include human waste, food scraps and chemicals.

Q4: State one of the reasons for increasing scarcity of fresh water.

Ans : Population growth.

Q5: Which day is celebrated as World Water Day?

Ans : 22 March

Q6: What is cleaning of water?

Ans : Cleaning of water is the process of removing pollutants before it enters a water body or is reused.

Q7: In order to have safe drinking water, it should be ________.

Ans : Boiled

Q8: What are the adverse effects of drinking contaminated water?

Ans : Drinking contaminated water results in diseases such as cholera, typhoid and diarrhoea. Polluted water can also prove fatal.

Q9: Water gets contaminated and scarcity of clean water is due to :

  • People take baths and wash clothes in rivers and lakes.
  • Many people bathe their animals in rivers and lakes.
  • Increase in the population, industries and improper disposal of waste
  • All of the above.

Ans : All of the above.

Q10: What is sewage treatment?

Ans : Pollutants in waste water can be removed in several stages, and this process is called “sewage treatment.

Q11: Sewage contains organic and _______________ impurities.

Ans : Inorganic

Q12: Sewage contains disease-causing bacteria. True/False

Ans : True

Q13: Saprotrophic bacteria feed on dead organisms.True/False

Ans : True

Q14: Sewage contains some harmful nutrients, such as ______________and nitrogen.

Ans : Phosphorous

Q15: Wastewater has many impurities and these impurities should be removed by _______________.

Ans : Water treatment.

Q16: What is the purpose of filtering waste water?

Ans : To remove large impurities.

Q17: What is a clarifier?

Ans : A clarifier is a tank with its central part inclined downwards so as to allow faeces to settle down. The inclined waste is then removed using a scraper.

Q18: Name some biological contaminants in water.

Ans : bacteria and microbes

Q19: Name the chemical used in water plant to clean water

Ans : Chlorine tablets or ozone.

Q20: Dried _ is used as manure.

Ans : Sludge

Q21: List the substances responsible for blockage of drain.

Ans : Tealeaves, solid food remains, soft toys, cotton, and sanitary towels.

Q22: Why should used tea leaves, solid food remains, etc. not be released in 

the drains?

Ans : Used tea leaves, solid food remains etc. should not be thrown down the drain as they may choke the drain.

Q23: What is the function of bar screens in waste water treatment plant?

Ans : The bar screen remove the large objects like rags, sticks, cans, plastics packets etc. from the sewage.

Q24: Why waste water is passed through bar screen?

Ans : Waste water is passed through bar screens to remove big objects like cans, sticks, rags etc.

Q25: What is the function of a skimmer?

Ans : A skimmer removes the floatable solids like oil, grease etc.

Q26: Why air is pumped into clarified water?

Ans : Air is pumped into clarified water to help aerobic bacteria to grow.

Q27: The suspended microbes in water treatment plant settle at the __________& the water is removed from the_____

Ans : Bottom and top.

Q28: State various uses of water.

Ans : Water is used for:

  • Drinking
  • Cooking
  • Washing clothes, utensils
  • Generating electricity
  • Bathing

Q29: What is the actual reason behind improper sanitation?

Ans : Lack of knowledge and of money, illiteracy, large population and lack of social awareness results in improper sanitation

Q30: Onsite sewage disposal systems collect human excreta and store it in a hole or a pipe, and later direct it to a sewage treatment plant. True/False.

Ans : True

Q31: Septic tanks are not suitable for places such as hospitals, isolated buildings and clusters of houses where there is no sewage.True/False

Ans : False

Q32: What kind of toilets are in aeroplanes and trains?

Ans : Chemical toilets

Q33: Public places such as railway stations, bus depots, airports and hospitals generate a lot of waste, which leads to diseases. True/False.

Ans : True

Q34: Solids like faeces settle at the bottom by _____________ and are removed with a scraper.

Ans : Sedimentation

Offer running on EduRev: Apply code STAYHOME200 to get INR 200 off on our premium plan EduRev Infinity!

Related Searches

past year papers


Semester Notes


Objective type Questions


Previous Year Questions with Solutions


Very Short Question Answers - Waste Water Story Class 7 Notes | EduRev






study material




Important questions


Very Short Question Answers - Waste Water Story Class 7 Notes | EduRev


video lectures


Extra Questions


Sample Paper


practice quizzes


shortcuts and tricks


Viva Questions








Very Short Question Answers - Waste Water Story Class 7 Notes | EduRev


mock tests for examination