1. In our country, there are attempts to increase the height of several existing dams like Tehri and Almati, dams across Narmada. What are the reasons behind it? Ans. Dams are large water storing bodies that are usually built by government agencies across the rivers to regulate the flow of water and generate electricity. They store huge amount of water for irrigation of fields throughout the year. 2. On the banks of the river, there are several factories that are discharging effluents into the river. The pH of water sample collected from the river is found to be acidic in the range of 3.5–4.5. Name the effluents which is the most likely to cause the lowering of pH of river water. What should be the effect of pollution on the fishes of the river . Ans. Untreated sewage, garbage, some human activities like bathing, washing of clothes and immersion of ashes or unburnt corpses are the most likely causes of lowering of pH of river water. It makes the water toxic and kills the aquatic o
CBSE NCERT SOLUTION, STUDY MATERIAL, NOTES,CTET, SAMPLE PAPER, SCIENCE, PHYSICS, CHEMISTRY, BIOLOGY, CBSE QUESTION PAPER, SAMPLE PAPER, CBSE Syllabus; CBSE Model Papers; BOARD Exam PAPER; ONLINE STUDY HELP, STUDY MATERIALS, For CLASS 6 to 12, PDF FILE, YouTube VIDEO for lessons.