UPSC Prelims 2020— Question 1

This question tests carbon nanotubes. The key concept is: Carbon nanotubes have high strength, electrical properties and a large surface area, enabling research in drug delivery, biosensing and engineered biomedical materials. The statement that they are biodegradable is not generally correct; their persistence and toxicological profile remain important research issues. The verified answer for the uploaded Set-B paper is option C. Option A — 1 and 2 only: This is not the correct option. The option does not match the verified combination or conclusion. The decisive point is the distinction explained above: Carbon nanotubes have high strength, electrical properties and a large surface area, enabling research in drug delivery, biosensing and engineered biomedical materials. The statement that they are biodegradable is not generally correct; their persistence and toxicological profile remain important research issues. Therefore this alternative should be eliminated even if part of its wording appears plausible in isolation. Option B — 2, 3 and 4 only: This is not the correct option. The option does not match the verified combination or conclusion. The decisive point is the distinction explained above: Carbon nanotubes have high strength, electrical properties and a large surface area, enabling research in drug delivery, biosensing and engineered biomedical materials. The statement that they are biodegradable is not generally correct; their persistence and toxicological profile remain important research issues. Therefore this alternative should be eliminated even if part of its wording appears plausible in isolation. Option C — 1, 3 and 4 only: This is the correct option. It matches the verified conclusion because Carbon nanotubes have high strength, electrical properties and a large surface area, enabling research in drug delivery, biosensing and engineered biomedical materials. The statement that they are biodegradable is not generally correct; their persistence and toxicological profile remain important research issues. The wording of the option is consistent with the governing concept tested by the question. Option D — 1, 2, 3 and 4: This is not the correct option. The option does not match the verified combination or conclusion. The decisive point is the distinction explained above: Carbon nanotubes have high strength, electrical properties and a large surface area, enabling research in drug delivery, biosensing and engineered biomedical materials. The statement that they are biodegradable is not generally correct; their persistence and toxicological profile remain important research issues. Therefore this alternative should be eliminated even if part of its wording appears plausible in isolation. For UPSC-style elimination, first identify the exact proposition being tested, then evaluate each statement independently before comparing the answer codes. Avoid treating a broad or absolute statement as correct merely because its general theme is familiar. The precise qualifiers in the question—such as 'all', 'only', 'cannot', 'largest', 'always' or a specific institutional role—often determine the answer. On that basis, option C is the verified answer.