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13 questions with worked solutions.
Answer: Clearing forest
Clearing forest directly removes trees and vegetation, which is counter to preserving or maintaining forests.
Q2. Ozone layer of upper atmosphere is being destroyed by
Answer: chlorofluorocarbon
Chlorofluorocarbons (CFCs) reach the upper atmosphere, where ultraviolet radiation breaks them down and releases chlorine radicals. These radicals catalytically destroy ozone molecules, thinning the ozone layer.
Q3. Biogas plant is more useful than burning of dung cakes because
Answer: Both A and B
Biogas plants are better because they produce clean fuel with much less smoke and air pollution than burning dung cakes. They also leave behind slurry that can be used as manure, so they provide both energy and fertilizer.
Q4. Drinking aerated drink with low levels (0.02 ppm) of pesticide for long period would cause
Answer: Accumulation in the body
Pesticides can be persistent and may not be fully eliminated after each exposure, so repeated intake can cause them to accumulate in body tissues. This is called bioaccumulation, which fits the long-term low-level exposure described.
Q5. The most rapidly depleting resource in the world is
Answer: Forest
Forests are rapidly depleted because trees are harvested and cleared much faster than they can regenerate. Water, wind, and sunlight are not depleted in the same way on a global scale.
Q6. Which of the following defines the effect of deforestation on environment?
Answer: Both A and B
Trees remove carbon dioxide from the air during photosynthesis, so cutting them down leaves more CO2 in the atmosphere. Higher CO2 strengthens the greenhouse effect, which leads to global warming, so both statements are correct.
Q7. Which of the following statements does not apply to eutrophication.
Answer: The nutrients such as sulphur and phosphorus encourage the growth of aquatic organisms in the lake
Eutrophication is the enrichment of a lake with nutrients that promote excessive plant and algal growth. Phosphorus is a key nutrient, but sulphur is not usually cited as a cause of eutrophication, so that statement does not properly apply.
Q8. Black-foot disease is caused due to ground water contaminated with excess of
Answer: Arsenic
Black-foot disease is a form of peripheral vascular disease caused by chronic arsenic exposure through contaminated groundwater. Arsenic damages blood vessels and tissues, leading to ischemia and the characteristic blackening of the feet.
Answer: UV radiation reaching earth
The ozone layer absorbs much of the Sun’s harmful ultraviolet radiation. When it thins, more UV radiation reaches Earth’s surface, increasing risks like skin cancer and eye damage.
Q10. is a grade between lignite and anthracite.
Answer: Bituminous coal
Bituminous coal is the middle rank in the coalification series, lying between lignite and anthracite. Lignite is lower-grade and anthracite is the highest-grade coal, so the grade between them is bituminous coal.
Q11. Which of the following would happen in the presence of greenhouse effect in the atmosphere?
Answer: The earth's surface temperature will increase
Greenhouse gases absorb and re-radiate outgoing infrared radiation, trapping more heat in the lower atmosphere. This raises the average temperature at Earth's surface.
Answer: Activated sludge treatment
Activated sludge treatment recycles a portion of the microbial-rich sludge back to the start so the decomposer population stays high and breaks down organic matter efficiently. This recycling of activated sludge is the defining feature of the process.
Q13. If the smog density of an area increases, it indicates
Answer: Vehicles of area is not under PUC norms
Smog density rises when more pollutants are released into the air, especially from vehicles. If many vehicles fail PUC norms, their emissions are higher, which increases smog.