18. Wastewater Story Class 7 Science [LATEST] Solutions topic -4 in English - CBSE Study
NCERT Solutions for Class 7 Science are carefully prepared according to the latest CBSE syllabus and NCERT textbooks to help students understand every concept clearly. These solutions cover all important 18. Wastewater Story with detailed explanations and step-by-step answers for better exam preparation. Each topic -4 is explained in simple language so that students can easily grasp the fundamentals and improve their academic performance. The study material is designed to support daily homework, revision practice, and final exam preparation for Class 7 students. With accurate answers, concept clarity, and structured content, these NCERT solutions help learners build confidence and score higher marks in their examinations. Whether you are revising a specific topic or preparing an entire chapter, this resource provides reliable and syllabus-based guidance for complete success in Science.
Class 7 English Medium Science All Chapters:
18. Wastewater Story
4. topic -4
Additional Question with solution:
Que: World water Day is celebrated on.
Ans: 22 March.
Que: Mention the period proclaimed as the International Decade for action on water for life.
Ans: 2005 - 2015 is the period proclaimed as the international Decade for action on water for life.
Que: Name the three processes involved in treatment of wastewater.
Ans: Treatment of watewater involves physical, chemical and biological processes for removing different types of contaminants.
Que: Explain sewers and sewage.
Ans: Sewers are the pipes acting as a transport system that carries sewage from point of origin to the point of disposal. The wastewater released from homes, industries, hospitals, offices and other uses is called swewge.
Que: The used water should not be wasted. Do you agree? Justify.
Ans: The used water should not be wasted but it should be cleaned.
Que: Bleaching powedr is mixed in water, why? Think and give appropriate reson for it.
Ans: Bleaching powder is mixed in water to make it safe for drinking because it kills the harmful germs present in water.
Que: Natural water is the purest from of water. Explain why or why not.
Ans: Natural water is not pure always. It is because all types of water except rainwater contain salts dissolved in it. Theses salts make the water impure.
Que: Mention the role of effluent treatment plants in cities.
Ans: The effluent treatment plants filter out undissolved materials from water.
Que: Protozoa is causative organism of which waterborne disease?
Ans: Dysentry.
Que: Saniation can be improved. Explain, what step should be taken to improve it.
Ans: Low cost onsite sewage disposal system must be encouraged to improve sanitation.
Que: Give the percentage of water being activated in sludge.
Ans: About 97% of water is being activated in sludge.
Que: Wastewater is fit for human consumption or not. give reason to support your.
Ans: No, because it is dirty and has many diseases causing organisms like cholera, typhoid, etc.
Que: Name two chemicals used to disinfect wastewater.
Ans: Chlorine and ozone.
Que: Special type to toilets has been designed in aeroplanes, name it.
Ans: Vacuum toilets.
Que: Name the toilets used in areas with limited water supply.
Ans: Vermi - processing toilets.
Que: Open drain is big concern now - a - days. Justify.
Ans: Open drain is big concern for the society now - a days because they create unhygienic conditions. It provides favourable conditions to filies, mosquitoes and unhygienic conditions. It provides favourable conditions to filies, mosquitoes and other insects to breed and spread a number of diseases.
Que: Sewage also contains some nutrients Comment.
Ans: Sewage is a complex mixture which contains suspended solids, organic and inorganic impurities, nutrients, saprotrophic and disease causing bacteria and other microbes.
The nutrients present in sewage are phosphorus and nitrogen.
Que: The terms sewage, sewers and sewerage are interlinked with each other. Can you explain, how?
Ans: The terms like sewage, sewage and sewerage are interlinked with other because sewage is a mixture of watewater coming out of homes and other places. Sewers are pipes which carry sewage and sewerage is a network of sewage carrying pipes.
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