Read the passage and answer the questions:
Water Pollution
Indiscriminate use of water by increasing population and industrial expansion has led degradation of the quality of water considerably. Surface water available from rivers, canals, lakes, etc. is never pure. It contains small quantities of suspended particles, organic and inorganic substances. When concentration of these substances increases, the water becomes polluted, and hence becomes unfit for use. In such a situation, the self-purifying capacity of water is unable to purify the water. Though water pollutants are also created from natural sources (erosion, landslides, decay and decomposition of plants and animals, etc.) pollutants from human activities are the real causes of concern. Human beings pollute the water through industrial, agricultural and cultural activities. Among these activities, industry is the most significant contributor. Industries produce several undesirable products including industrial wastes, polluted waste water, poisonous gases, chemical residuals, numerous heavy metals, dust, smoke, etc. Most of the industrial wastes are disposed off in running water or lakes. Consequently, poisonous elements reach the reservoirs, rivers and other water bodies, which destroy the bio-system of these waters. Major water polluting industries are leather, pulp and paper, textiles and chemicals. Various types of chemicals used in modern agriculture such as inorganic fertilisers, pesticides and herbicides are also pollution generating components. These chemicals are washed down to rivers, lakes and tanks. These chemicals also infiltrate the soil to reach the ground water. Fertiliser induces an increase in the nitrate content of surface waters. Cultural activities such as pilgrimage, religious fairs, tourism, etc. also cause water pollution. In India, almost all surface water sources are contaminated and unfit for human consumption.
Which of the following factors is mainly responsible for increasing water pollution?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Population explosion and industrial expansion
Option (1) Decreasing water demand — Incorrect. Less demand would ease the pressure on water, not pollute it.
Option (2) Easy availability of water — Incorrect. The passage blames the indiscriminate use of water, not how easily it is found.
Option (3) Rapid growth of coral reefs — Incorrect. Coral reefs grow in the sea and have no part in polluting rivers and lakes.
Option (4) Population explosion and industrial expansion — Correct. A growing population uses more water and sends more of it back dirty, and expanding industries dispose of their wastes in running water or lakes. This indiscriminate use of water by more people and more industry has degraded its quality considerably.
NCERT (2025-26): “Water Pollution … Indiscriminate use of water by increasing population and industrial expansion has led degradation of the quality of water considerably. Surface water available from rivers, canals, lakes, etc. is never pure. It contains small quantities of suspended particles, organic and inorganic substances. When concentration of these substances increases, the water becomes polluted, and hence becomes unfit for use. In such a situation, the self-purifying capacity of water is unable to purify the water.” |