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100 questions in this collection · Page 2 of 10
Question 11 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the water hyacinth (Eichhornia crassipes):
I. It is considered the world's most problematic aquatic weed. II. It was introduced to India because of its beautiful purple flowers and leaf shapes. III. It grows faster than our capacity to clear it, earning the name 'Terror of Bengal'. IV. It thrives in clean, nutrient-deficient lakes by restoring oxygen levels.
Which of the statements given above are correct?
Water hyacinth is the world's most problematic aquatic weed. It was introduced because of its attractive flowers, grows extremely rapidly, and is known as the 'Terror of Bengal'. It thrives in nutrient-rich polluted waters and depletes oxygen rather than restoring it.
Question 12 of 100
📘 CLASS XII
Environmental Issues
The following statements relate to the process of Biomagnification:
I. Biomagnification refers to an increase in the concentration of a toxicant at successive trophic levels. II. Toxicants like DDT and mercury cannot be metabolized or excreted, so they accumulate in organisms. III. If the water has a DDT concentration of 0.003 ppm, fish-eating birds can reach a toxic level of 25 ppm. IV. High concentrations of DDT interfere with calcium metabolism in birds, causing thinning of eggshells and premature breaking.
Which of the statements given above are correct?
Statement III is incorrect because the initial concentration of DDT in water is 0.003 ppb, not ppm. Biomagnification results in about 25 ppm in fish-eating birds, and DDT interferes with calcium metabolism causing eggshell thinning.
Question 13 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the Natural Eutrophication of lakes:
I. Natural eutrophication is the natural aging of a lake by nutrient enrichment of its water. II. In a young lake, the water is cold and clear, supporting very little organic life. III. Over centuries, as silt and organic debris pile up, the lake grows deeper and colder. IV. Marsh plants take root in the shallows, eventually converting the lake basin into land.
Which of the statements given above are correct?
Natural eutrophication is the natural aging of lakes. Young lakes are cold and clear with little organic life. As sediments accumulate, lakes become shallower and warmer, allowing marsh plants to colonize and gradually convert the basin into land. Statement III is incorrect.
Question 14 of 100
📘 CLASS XII
Environmental Issues
With reference to Cultural Eutrophication and Thermal Wastewater, read the following statements:
I. Cultural or accelerated eutrophication is caused by human activities like sewage and industrial waste discharge. II. Nitrates and phosphates are the primary contaminants that accelerate eutrophication by acting as plant nutrients. III. Thermal wastewater from power plants eliminates or reduces temperature-sensitive organisms. IV. Thermal wastewater has a strictly negative effect and cannot enhance the growth of any organism under any conditions.
Which of the statements given above are correct?
Cultural eutrophication is caused by human activities. Nitrates and phosphates stimulate excessive plant growth. Thermal wastewater harms temperature-sensitive organisms but may enhance growth in extremely cold areas. Hence Statement IV is incorrect.
Question 15 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding the integrated wastewater treatment system in Arcata, California:
I. The project was developed by the town of Arcata in collaboration with biologists from Humboldt State University. II. The cleaning process combines conventional sedimentation and filtration with natural marsh biology. III. The natural treatment consists of six connected marshes spread over 60 hectares of marshland. IV. The upkeep and safeguarding of this project are managed by a citizens group called FOAM.
Which of the statements given above are correct?
All the statements are correct. The Arcata Marsh project combines conventional wastewater treatment with natural marsh purification through six connected marshes and is maintained by Friends of the Arcata Marsh (FOAM).
Question 16 of 100
📘 CLASS XII
Environmental Issues
Ecological Sanitation (EcoSan) toilets are described in the following statements:
I. EcoSan is a sustainable system for handling human excreta using dry composting toilets. II. It is a practical, hygienic, and efficient method that completely avoids the use of water. III. It allows human excreta to be recycled into organic fertilizer, reducing the need for chemical fertilizers. IV. EcoSan toilets are currently operational in several areas of Kerala and Sri Lanka.
Which of the statements given above are correct?
All four statements are correct. EcoSan toilets use dry composting, require no water, convert human waste into organic manure, reduce dependence on chemical fertilizers, and are successfully used in parts of Kerala and Sri Lanka.
Question 17 of 100
📘 CLASS XII
Environmental Issues
Read the following statements regarding Solid Waste Management and Sanitary Landfills:
I. Sanitary landfills were adopted as a clean substitute for open-burning dumps. II. In a landfill, wastes are compacted in a trench and covered with dirt every day. III. Landfills are a highly successful, permanent solution because waste degrades completely without any risk of groundwater contamination.
Which of the statements given above are correct?
Sanitary landfills were adopted as a cleaner alternative to open-burning dumps. In landfills, waste is compacted in trenches and covered daily with soil. However, they are not a permanent solution because leachates may contaminate groundwater and landfills fill up rapidly.
Question 18 of 100
📘 CLASS XII
Environmental Issues
The following statements relate to the Bengaluru case study of plastic waste management (Ahmed Khan):
I. Ahmed Khan developed Polyblend, a fine powder of recycled, modified plastic. II. Polyblend is mixed with bitumen to lay roads, enhancing the water-repellent properties of bitumen. III. Using the blend of Polyblend and bitumen increases road life by a factor of ten. IV. By 2002, more than 40 km of road had already been laid in Bangalore using this technique.
Which of the statements given above are correct?
Ahmed Khan developed Polyblend from recycled plastic waste. Mixed with bitumen, it improves the water-repellent property of roads. Road life increases by about three times, not ten. By 2002, over 40 km of roads had been laid using this technology.
Question 19 of 100
📘 CLASS XII
Environmental Issues
Consider the following statements regarding Electronic Waste (e-waste) management:
I. Over half of the e-wastes generated in the developed world are exported to developing nations like India, China, and Pakistan. II. Recycling of e-waste allows the recovery of valuable metals like copper, iron, silicon, nickel, and gold. III. Recycling in developing countries is highly safe because it is fully automated with zero human contact.
Which of the statements given above are correct?
More than half of the e-waste from developed countries is exported to developing countries. Recycling helps recover valuable metals such as copper, iron, silicon, nickel, and gold. Recycling in developing countries is often manual and exposes workers to toxic substances, making Statement III incorrect.
Question 20 of 100
📘 CLASS XII
Environmental Issues
Read the following statements regarding Ramesh Chandra Dagar's organic farming in Haryana:
I. He practices integrated organic farming, which is a zero-waste, cyclical procedure. II. His farm integrates bee-keeping, dairy management, water harvesting, composting, and agriculture. III. Composting allows natural fertilizer production, making chemical fertilizers unnecessary. IV. To support organic farmers, he founded the Haryana Kisan Welfare Club, which now has a membership of 5,000 farmers.
Which of the statements given above are correct?
All the statements are correct. Ramesh Chandra Dagar demonstrated an integrated organic farming model based on zero waste and resource recycling, while the Haryana Kisan Welfare Club supports about 5,000 farmers.