VKC ScienceChemistry for written exams Telegram

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

Q2(c)(i). Limiting radius ratio for coordination numbers 3 and 6

Question

Calculate the limiting radius ratio for the crystals with coordination number 3 and 6.

Answer in brief

Coordination number 3: r⁺/r⁻ = 2/√3 − 1 = 0.155; coordination number 6: r⁺/r⁻ = √2 − 1 = 0.414.

Part of VKC Basic

Read the key points and the full model answer with VKC Basic

VKC Basic (₹999 for 6 months) opens every solved answer, the notes, the handbook and the daily answer archive. Every Mains test series includes it.

See what is included Already a member? Sign in

The full model answer

As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.

The handwritten model answer pages open with the VKC plan.
Read the whole 2024 solution2024 question paper

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

Coverslimiting radius ratiocoordination numbertrigonal planaroctahedral voidrock-salt structure

All parts of Question 2