UPSC Combined Geo-Scientist, Mains · 2021 · Mains Paper I
Q2(c)(i). Metal deficiency in wüstite
Question
The compound FeₓO generally has x < 1. Describe the probable metal defect that leads to x being less than 1.
Answer in brief
Iron vacancies, compensated by oxidation of some Fe²⁺ to Fe³⁺, give a metal-deficient oxide.
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CoverswüstiteFexOnon-stoichiometrymetal deficiency defectcation vacancyFe0.95O
All parts of Question 2
- 2(a) ReO₃ unit cell and perovskite relation10 marks
- 2(b) Doping gallium arsenide10 marks
- 2(c)(i) Metal deficiency in wüstite5 marks
- 2(c)(ii) Solid-state and solution synthesis5 marks