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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper II covers physical chemistry.

UPSC Combined Geo-Scientist, Mains · 2017 · Mains Paper II

Q8(a). Time for 99.9 percent completion

Question

Show that a first-order reaction takes approximately ten half-lives to reach 99.9% completion.

Answer in brief

t_(99.9)/t_(1/2)=ln 1000/ln 2=9.966≈10.

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CoversTime for 99.9 percent completionChemical kinetics

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