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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 · 2021 · Mains Paper II

Q10(b). Molecular diameter of helium from the van der Waals b

Question

Calculate the molecular diameter (d) of helium if its Van der Waals constant b is 23.70 cm³ mol⁻¹.

Answer in brief

d = 2.66 × 10⁻¹⁰ m = 266 pm = 2.66 Å.

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Topic notes: real gases, the van der Waals equation, critical constants and Boyle temperature, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coversvan der Waals constant bexcluded volumemolecular diameterheliumcollision diameter

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