2001 General Studies, all questions

UPSC Prelims 2001 · General Studies

Question 117: Science and Technology

Which one of the following is NOT radioactive?

aAstatine
bFrancium
cTritium
dZirconium

AnswerThe answer is (d).

Zirconium is treated as non-radioactive; its natural isotopes are stable or have such extremely long half-lives that they are of no practical concern. Astatine and francium have no stable isotopes at all, and tritium, the hydrogen isotope with two neutrons, is radioactive with a half-life of about 12 years. Remember that every element beyond bismuth (atomic number 83) is radioactive.

Why each option is right or wrong
  • (a) Astatine has no stable isotope.
  • (b) Francium has no stable isotope.
  • (c) Tritium is radioactive, with a half-life of about 12 years.
  • (d) Right: zirconium is treated as non-radioactive.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2001, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.