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

Q5(b)(i). How water condenses onto glass

Question

How does water condense onto glass?

Answer in brief

Water vapour condenses on glass that is below the dew point; clean glass is hydrophilic, its surface OH groups hold water by hydrogen bonds, so nuclei form on the surface easily and spread into a film.

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: adsorption isotherms, heterogeneous catalysis and colloids, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coverscondensationheterogeneous nucleationKelvin equationcontact angledew pointadsorption

All parts of Question 5