NCERT solution for class 7// Science //Chapter 18 - Wastewater story
NCERT solution > class 7 > Science Chapter 18 - Wastewater story Exercise Q1. Fill in the blanks 1. Cleaning of water is a process of removing pollutants 2. Wastewater released by houses is called sewage . 3. Dried sludge is used as manure . 4. Drains get blocked by cooking oil and fats Q2. What is sewage explain why it is harmful to discharge untreated sewage into rivers or seas? Answer - Sewage is the waste water containing both liquid and solid impurities from homes, industries, hospital, officers it contain the various contamination include disease-causing bacteria organic and inorganic waste etc. If untreated sewage is discharged into rivers or sea then it polluted the water and unsafe for drinking it also can cause Cholera typhoid and dysentery like disease so it is harmful to discharge untreated sewage into the rivers or sea Q3. Why should oils and fat be not released in the drain explain. Answer - oil and fats deposited o...