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UPSC Prelims 2025 GS Paper 1, question 50

Topic: Environment and ecology

Q50

Consider the following statements :

Statement-I : Activated carbon is a good and an attractive tool to remove pollutants from effluent streams and to remediate contaminants from various industries.

Statement-II : Activated carbon exhibits a large surface area and a strong potential for adsorbing heavy metals.

Statement-III : Activated carbon can be easily synthesized from environmental wastes with high carbon content.

Which one of the following is correct in respect of the above statements?

  1. (a) Both Statement-II and Statement-III are correct and both of them explain Statement-ICorrect answer
  2. (b) Both Statement-II and Statement-III are correct but only one of them explains Statement-I
  3. (c) Only one of the Statements II and III is correct and that explains Statement-I
  4. (d) Neither Statement-II nor Statement-III is correct

Solution.

Answer: (a) Both Statement-II and Statement-III are correct and both of them explain Statement-I

  1. Statement-I is correct: activated carbon is widely used as an effective and economical adsorbent to remove organic pollutants and heavy metals from industrial effluents.
  2. Statement-II is correct and explains Statement-I: its highly developed microporous structure gives activated carbon a massive internal surface area (500500 to 1500 m2/g1500\text{ m}^2/\text{g}) and surface functional groups that strongly adsorb heavy metals and contaminants.
  3. Statement-III is correct and explains Statement-I: activated carbon can be inexpensively synthesized from carbon-rich agricultural and environmental wastes (such as coconut shells, rice husks, and sawdust), explaining why it is an attractive and cost-effective remediation tool.

Trap: If Statement-III is viewed as explaining only the low cost/sustainability ('attractive') while only Statement-II explains the physical mechanism of pollutant removal, option (b) is the narrower reading.