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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

Q8(b)(i). Possible arrangements and shape of ClF₃

Question

Draw all the possible structural dispositions of the ClF₃ molecule. Establish logically which will be the most favoured disposition. Comment on the shape of the ClF₃ molecule.

Answer in brief

Arrangement I, with both lone pairs in equatorial positions, is the most favoured; ClF₃ is T-shaped, slightly bent (F–Cl–F = 87.5°).

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Topic notes: VSEPR, hybridisation and Bent's rule, with every Civil Services, IFoS and Geo-Scientist PYQ →

Topic notes: main group chemistry: boranes, borazine, phosphazenes, silicates, silicones, interhalogens, xenon and sulfur–nitrogen compounds, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversVSEPR theoryClF₃T-shaped moleculelone pair repulsiontrigonal bipyramidinterhalogen compounds

All parts of Question 8