Oxidation states of the metal in the minerals haematite and magnetite, respectively, are

Oxidation states of the metal in the minerals haematite and magnetite, respectively, are
  1. II, III in haematite and III in magnetite
  2. II, III in haematite and II in magnetite
  3. II in haematite and II, III in magnetite
  4. III in haematite and II, III in magnetite

Solution

Haematite is $\mathrm{Fe}_2 \mathrm{O}_3$, in which oxidation number of iron is III. Magnetite is $\mathrm{Fe}_3 \mathrm{O}_4$ which is infact a mixed oxide (FeO $\cdot \mathrm{Fe}_2 \mathrm{O}_3$ ) hence, iron is present in both II and III oxidation state.

Asked in: JEE Advanced 2011 (Paper 2)

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