An element shows the SAME oxidation number in all its compounds. Which is it?
AFluorine
BOxygen
CSulphur
DManganese
Answer & Solution
Correct answer: A. Fluorine
1. Fluorine is the MOST ELECTRONEGATIVE element, so in every compound it has oxidation state −1.
2. Oxygen is usually −2 but +2 in OF₂ and −1 in peroxides — not constant.
3. S has −2, +2, +4, +6; Mn ranges from +2 to +7.
_Source: NCERT Class 11 Chem Ch 8 §8.3 Rules for Oxidation Number_
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