Oxygen Paramagnetic — FRCA Primary MCQ
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Correct answer: B — It has two unpaired electrons
Oxygen has two unpaired electrons making it paramagnetic (attracted into a magnetic field). The paramagnetic oxygen analyser exploits this: nitrogen-filled glass spheres on a torsion wire are displaced when oxygen is drawn into a magnetic field proportional to oxygen concentration.
Reference: Al-Shaikh Stacey 2019 Essentials of Anaesthetic Equipment