The Correct Answer and Explanation is:
Based on the questions provided in the image, here are the correct answers and a detailed explanation.
The correct answers are:
- Question 27: d. salts and acids
- Question 28: c. Disease-causing agents like bacteria and viruses
- Question 29: d. Coastal run-off
- Question 30: b. No
Explanation
For Question 27, the correct answer is salts and acids. The question asks for an inorganic pollutant. Inorganic compounds are substances that do not contain carbon-hydrogen bonds and are typically not derived from living organisms. Salts, such as those from road deicing or irrigation, and acids, like sulfuric acid from industrial discharge or acid rain, fit this definition. In contrast, the other options are organic pollutants. Sewage, animal waste, and oil spills are all derived from living or once-living matter and are composed of complex carbon-based molecules.
For Question 28, the correct answer is disease-causing agents like bacteria and viruses. The question specifically seeks a pollutant type that causes disease. These microscopic organisms, also known as pathogens, are directly responsible for waterborne illnesses such as cholera, typhoid, and dysentery when present in freshwater ecosystems. While other pollutants are harmful, they act differently. Toxic wastes may cause poisoning or long term health issues like cancer. Thermal pollution alters water temperature, harming aquatic life. Oxygen-demanding wastes, like sewage, deplete dissolved oxygen, which can kill fish, but the diseases are caused by the pathogens that these wastes often carry.
For Question 29, the most accurate answer is coastal run-off. This term is comprehensive and represents the primary mechanism for water quality degradation in coastal zones. Coastal run-off includes all the contaminants washed from the land into the ocean. This encompasses industrial wastes, agricultural chemicals, urban stormwater carrying oil and trash, and poorly treated sewage. Because it gathers pollutants from numerous widespread sources, it is considered the principal cause of coastal water pollution, being a more encompassing answer than industrial wastes or tourism alone.
For Question 30, the answer is unequivocally No. While groundwater is naturally replenished through a process called recharge, this process is often extremely slow, sometimes taking decades or centuries. Human activities, particularly large scale agriculture and urban water supply, can extract groundwater at a rate that far exceeds its natural replenishment. This over-extraction leads to the depletion of aquifers, falling water tables, land subsidence, and, in coastal regions, saltwater intrusion into freshwater supplies. Therefore, groundwater is a finite resource that must be managed sustainably, not consumed without limitation.
