Indian Forest Service (Mains), Chemistry optional · 2025 · Paper II

Q7(a)(ii). Preparation and branching of silicones

10 marks
Topic: Preparation and properties of polymers
Question only

Question

Give the mechanism of silicone synthesis from dialkyldichlorosilane and explain how branching is introduced.

Model answer

The free solution for 2025 answers questions 1, 3, 4, 5 and 8, the ones picked in its time plan. This part is not answered on the site yet. New answers are announced on Telegram.

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Topic notes: polymers: polymerisation, Ziegler–Natta and molar mass, with every Civil Services, IFoS and Geo-Scientist PYQ →

Coverssiliconesdialkyldichlorosilane hydrolysissilanol condensationcross-linking with RSiCl₃polysiloxane

All parts of Question 7

7(a)(i) Polyphosphazene formation and solubility10 marks
7(a)(ii) Preparation and branching of silicones10 marks
7(b)(i) Checking the conjugated chromophore5 marks
7(b)(ii) Conjugated and non-conjugated ketones5 marks
7(c) Five reagent-based transformations10 marks