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Important Questions for Class 12 Chapter 16:
Environmental Issues
(For college students & competitive exams)
Q.1. Why is lead-free petrol or diesel recommended to reduce pollutants emitted by automobiles?
Answer: Diesel and petrol are added with lead in the form of Pb(CH3)4b and Pb(C2H5)4 as an antiknock agent.
Q.2. To include noise as air pollution, in which year was the Air Prevention and Control of Pollution Act amended?
Answer: 1987.
Q.3. Which city in India has all the public road transport running on CNG?
Answer: Delhi.
Q.4. What is a possible source of silt that gets accumulated in water tanks?
Answer: Soil particles that are carried out with water from rivers and deep borewells etc.
Q.5. Define cultural eutrophication.
Answer: It is a phenomenon wherein effluents from homes and industries fuel the cultural and natural aging process of water bodies which otherwise takes thousands of years.
Q.6. Write two severe effects of particulate matter on human health.
Answer: Inflammation. Damage to the lungs and premature death.
Q.7. Name the raw material for polyblend.
Answer: They are made by a mixture of two or multiple polymers, mainly plastic waste products.
Q.8. Why does the road life factor increase by a factor of three upon the addition of blends of bitumen and poly blend?
Answer: Plastic increases the melting point of bit that prevents its melting given India’s hot climatic conditions, where the temperature frequently crosses 50℃. Because of the plastic blend, rainwater will not be able to penetrate.
Q.9. List two examples of plants that are used in agricultural fields as windbreakers.
Answer: The Calotropis and Vetia act as windbreakers.
Q.10. Write the name of an industry which can cause – eutrophication, thermal and air pollution.
Answer: Thermal power plants, chemical fertilizer units, smelting, refineries, metallurgical processing units, steel mills cause these pollutions. It may result in eutrophication is chemical is released from these industries.
Q.11. Define algal bloom.
Answer: Presence of organic matter in water acts as a food source resulting is extensive growth of planktonic algae in water bodies and is called an algal bloom.
Q.12. What is biomagnification?
Answer: Increase in the concentration of toxic substances at consecutive trophic levels in the food chain is referred to as biomagnification.
Q.13. List the three major impurities found in domestic wastewater.
Answer: Biodegradable organic matter, Pathogenic microbes, dissolved salts such as nitrates and phosphates.
Q.14. Define reforestation.
Answer: It is the process of restoring a forest that existed once but was removed at some point in the past.
Q.15. How can electronic wastes be treated in the most efficient way?
A.15. Recycling. It has two advantages:
Ozone Depletion.
Greenhouse Effect.
Global Warming.
Desertification.
Deforestation.
Climate Change.
Loss of Biodiversity.
Disposal of Wastes.
Pollutions.
Overpopulation.
Q.20.What is Solid Waste Management?
Solid-waste management is defined as the discipline associated with the generation, storage, collection, transfer and transport, processing, and disposal of solid waste in a manner that it does not have a harmful effect on the environment.
Short Answer Type Questions
Q.1. Can curtains and carpets positioned on the floor or surfaces of walls reduce the noise level? Justify your answer.
A.1. Yes, it can. They act as muffling devices and absorb sounds of moderate level.
Q.2. With advantages and suitable examples, explain hybrid vehicle technology.
A.2. It is a technology used to run vehicles on dual modes like compressed natural gas or petrol. CNG is a green and clean fuel so it is useful to decrease environmental pollution and also conserve petrol fossil fuel.
Q.3. Will water turn septic if dissolved oxygen level drops to zero? Which factor could lower the dissolved content of oxygen of an aquatic body.
A.3. Yes, it can turn septic. Fertilizers in aquatic bodies are responsible for lowering the level of dissolved oxygen.
Q.4. Listing a greenhouse gas, write its possible source of production on a larger scale. What are its harmful effects?
A.4. Some common greenhouse gases are carbon dioxide, methane, an oxide of nitrogen, water vapour, etc. Due to large scale deforestation, unlimited burning of fossil fuels causes the level of carbon dioxide to increase thus leading to global warming. Incomplete decomposition by anaerobic methanogens, garbage dump, flooded paddy field and marshy land is few of the sources leading to an increase in the levels of methane. Rice fields of Asia, release about 90% of methane.
Further Reading: Putrefaction
Q.5. Is planting trees and shrubs near boundary walls of buildings a common practice? Write about its usage.
A.5. Yes, it is. It acts as a boundary for sound and checks noise pollution. It also keeps a check on primary air pollutants such as dust, flies ash, etc.
