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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

Q3. Orthorhombic cell: Bravais lattice and d₂₂₂

Question

The parameters of a unit cell are given below: a = 0.487 nm, b = 0.646 nm, c = 0.415 nm, α = β = γ = 90°. Identify the Bravais lattice. Calculate the interplanar distance for (2 2 2) set of planes.

Answer in brief

a ≠ b ≠ c, all angles 90°: orthorhombic, primitive (P). d₂₂₂ = 0.142 nm (141.9 pm).

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Topic notes: crystal systems, Bragg's law, X-ray diffraction and radius ratio, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversBravais latticeorthorhombicinterplanar spacingMiller indicesd-spacing