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.

All topics
Paper I, physical and inorganic chemistry

Thermodynamics: every question, 2021 to 2025

17 parts worth 155 marks have been set on this unit in UPSC CSE Chemistry Paper I from 2021 to 2025. Each one opens on its own page with the question, the answer in brief and the key points.

Syllabus

Work, heat and internal energy; first law of thermodynamics. Second law of thermodynamics; entropy as a state function, entropy changes in various processes, entropy–reversibility and irreversibility, free energy functions; thermodynamic equation of state; Maxwell relations; temperature, volume and pressure dependence of U, H, A, G, Cp and Cv, α and β; J-T effect and inversion temperature; criteria for equilibrium, relation between equilibrium constant and thermodynamic quantities; Nernst heat theorem, introductory idea of third law of thermodynamics.

  • 17 parts
  • 155 marks
  • Marks by year:
  • 2025: 30
  • 2024: 35
  • 2023: 40
  • 2022: 30
  • 2021: 20
Cover of UPSC Civil Services (Main) Chemistry Paper I: Model Answers 2021 to 2025
Printed copy and Kindle

UPSC Civil Services (Main) Chemistry Paper I: Model Answers 2021 to 2025

  • All eight questions of each paper, with the question printed above its answer
  • Question choice and time plan for each paper
  • Topic-wise weightage and a topic-wise index