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?
Answer & explanation
Answer: (a) Both Statement II and Statement III are correct and both of them explain Statement I
Both Statement II and Statement III are correct, and both explain Statement I. A large surface area lets activated carbon hold heavy metals and other pollutants on its surface, and because it can be made cheaply from carbon-rich waste, it becomes an attractive tool for cleaning effluents.
- ✓ II Activated carbon is highly porous, with a very large surface area and strong adsorption capacity. Pollutants stick to that surface (adsorption), which is exactly how it strips heavy metals from wastewater. This explains why it removes pollutants (Statement I).
- ✓ III Farm and other carbon-rich wastes are the usual raw material for activated carbon, and the process is simple and cheap. This low cost explains why it is 'attractive' as a treatment tool (Statement I).
- ✗ (b) This option says only one of II and III explains Statement I. But the ability to adsorb (II) explains the 'good' part and the cheap, waste-based supply (III) explains the 'attractive' part, so both explain it.
- ✗ (d) Both statements are supported by published research on biomass-derived activated carbon, so 'neither is correct' fails.
Remember · Activated carbon = porous, huge surface area, strong adsorbent, cheaply made from carbon-rich waste; hence widely used to clean effluents.
Sources
- Adsorption of heavy metal onto biomass-derived activated carbon: review (RSC Advances, via NIH/PMC) ↗ “Biomass-derived activated carbon adsorbents offer large adjustable specific surface area, hierarchically porous structure, strong adsorption capacity, and excellent high economic applicability. … Agricultural waste is usually the first choice to prepare biomass-derived activated carbon, attributing to its high specific surface area, high stability, excellent adsorption properties, simple production process and low price.”
Question and answer: UPSC's official GS Paper I (2025, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·