Answer: Excessive algal growth in water bodies due to excess nutrients (nitrogen and phosphorus), leading to oxygen depletion.
- A A type of soil erosion caused specifically by overgrazing of grasslands and the unchecked clearing of forest cover over time
- B Excessive algal growth in water bodies due to excess nutrients (nitrogen and phosphorus), leading to oxygen depletion
- C An increase in water pH caused by the very gradual dissolution of carbonate mineral deposits over many decades
- D Desertification of previously fertile agricultural land due to prolonged seasonal drought conditions across multiple years
Correct answer: B. Excessive algal growth in water bodies due to excess nutrients (nitrogen and phosphorus), leading to oxygen depletion
Explanation: Eutrophication: excess nutrients (N, P from fertilizers/sewage) cause massive algal blooms. When algae die, decomposition consumes oxygen (dead zone). Fish and other organisms suffocate. Lakes and coastal waters are most affected. Solution: reduce nutrient runoff.
Sunlight passes through the atmosphere and warms the surface; the surface re-radiates this energy as infrared heat, which greenhouse gases (CO₂, CH₄, water vapour) absorb and trap - a naturally beneficial process that intensifies into global warming as gas concentrations rise from human activity.
Concept context
Pollution, global warming, ozone depletion, deforestation, and sustainability. Important for NEET and general awareness.