1997 General Studies, all questions

UPSC Prelims 1997 · General Studies

Question 114: Science and Technology

Which one of the following is paramagnetic in nature?

aIron
bHydrogen
cOxygen
dNitrogen

AnswerThe answer is (c).

Oxygen molecules have two unpaired electrons, so oxygen is attracted into a magnetic field: it is paramagnetic, and liquid oxygen clings to a strong magnet. Hydrogen and nitrogen molecules have all their electrons paired and are diamagnetic. Iron is magnetic in a stronger way, ferromagnetic, which is more than ordinary paramagnetism.

Why each option is right or wrong
  • (a) Iron is ferromagnetic, a much stronger effect than paramagnetism, so it is not the intended answer.
  • (b) Hydrogen has paired electrons and is diamagnetic.
  • (c) Right: oxygen has two unpaired electrons.
  • (d) Nitrogen has paired electrons and is diamagnetic.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 1997, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.