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UPSC Civil Services (Mains)

Chemistry optional

  • 2 papers
  • 250 marks each
  • 3 h per paper
  • 5 of 8 questions, Q1 and Q5 compulsory

Paper I covers physical and inorganic chemistry.

UPSC Civil Services (Mains), Chemistry optional · 2024 · Paper I

Q6(a)(ii). Molar extinction coefficient from 50 % transmission

Question

On passing monochromatic light through a 0.04 molar solution kept in a cell of thickness 2 cm, the intensity of the transmitted light was reduced to 50 %. Calculate the molar extinction coefficient.

Answer in brief

ε = 3.76 L mol⁻¹ cm⁻¹.

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Topic notes: photochemistry (quantum yield, Jablonski diagram, H₂–halogen reactions), with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversBeer–Lambert lawmolar extinction coefficientabsorbancetransmittancemolar absorptivity

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