2007 General Studies, all questions

UPSC Prelims 2007 · General Studies

Question 104: Science and Technology

Which one of the following non-metals is NOT a poor conductor of electricity?

aSulphur
bSelenium
cBromide
dPhosphorus

AnswerThe answer is (b).

Sulphur, phosphorus and bromine are non-metals that conduct electricity very poorly. Selenium is the exception here: grey selenium is a semiconductor whose conductivity rises sharply in light, so it is not a poor conductor in the same sense. (The option reads 'bromide' but means bromine.)

Why each option is right or wrong
  • (a) Sulphur is a poor conductor.
  • (b) Correct: selenium is a semiconductor.
  • (c) Bromine is a poor conductor.
  • (d) Phosphorus is a poor conductor.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2007, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.