UPSC Combined Geo-Scientist, Mains · 2025 · Mains Paper I
Q8(a). Redox indicators; ferroin
Question
What are redox indicators? Mention the criteria of a suitable redox indicator. What is ferroin? Draw the structures of ferroin in oxidised and reduced forms. Mention the colour(s) in these two forms.
Model answer
The free solution for 2025 answers questions 1, 3, 4, 6, 9 and 10, the ones picked in its time plan. Question 8 is answered in full in the Geo-Scientist Chemistry Paper I, 2021 to 2025 book, with every part of every paper.
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.
Printed copy and Kindle
UPSC Combined Geo-Scientist (Main) Chemistry Paper I: Model Answers 2021 to 2025
- All eleven questions of each paper, with the question printed above its answer
- Titration, gravimetric and nuclear numericals worked with units; structures drawn
- Topic-wise weightage and a topic-wise index
Coversredox indicatorsferroin1,10-phenanthrolineferriincolour change interval
All parts of Question 8
- 8(a) Redox indicators; ferroin15 marks
- 8(b) Consequences of the lanthanide contraction15 marks