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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 · 2023 · Mains Paper II

Q10(b). Quantum yield of the photodecomposition of HI

Question

The photodecomposition of hydrogen iodide vapour was carried out with a light source having wavelength of 2100 Å. Absorption of each calorie of light gave 1.44 × 10⁻⁵ g of hydrogen. What will be its quantum yield?

Answer in brief

ϕ(HI) = 1.945 ≈ 2 (two HI molecules decomposed per photon); ϕ(H₂) = 0.97 ≈ 1.

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Coversquantum yieldeinsteinHI photolysisphotochemistry numericalphotodecomposition

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