Q3(a). Calcium in a phosphate medium by AAS; protective agents
(i) Why does AAS analysis of calcium in a phosphate buffer solution give poor result? Suggest a method to improve the determination of calcium by AAS in the above solution. (ii) Take an example to describe how protective agents improve AAS analysis.
Model answer
The free solution for 2025 answers questions 1, 2, 4, 6, 7 and 9, the ones picked in its time plan. Question 3 is answered in full in the Geo-Scientist Chemistry Paper III, 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.
UPSC Combined Geo-Scientist (Main) Chemistry Paper III: Model Answers 2021 to 2025
- All ten questions of each paper, with the question printed above its answer
- Instruments drawn as labelled diagrams, numericals worked with units
- Topic-wise weightage and a topic-wise index
Coverschemical interferencephosphate interference calciumreleasing agentprotective agentEDTAAAS
All parts of Question 3
- 3(a) Calcium in a phosphate medium by AAS; protective agents15 marks
- 3(b) Two-line background correction in AAS5 marks
- 3(c) Globar as an IR source; advantage over the Nernst glower10 marks