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JEE Main levelSingle correct optionDifficulty 2 of 3rx015

Magnetite, $Fe X_{3} O X_{4}$ , is a mixed oxide. Using the INDIVIDUAL (not average) oxidation numbers, the three iron atoms in one formula unit are

Aall three at $+ 8/3$
Btwo at $+ 2$ and one at $+ 3$
Cone at $+ 2$ and two at $+ 3$
Done at $+ 2$ and two at $+ 4$

Answer: C

Total positive charge needed is

4 \times 2 = 8

. Treating it as

FeO \cdot Fe X_{2} O X_{3}

gives one

Fe^{2 +}

and two

Fe^{3 +}

:

2 + 3 + 3 = 8

. The option with two

+ 2

and one

+ 3

sums to 7 only, and

+ 8/3

is the average, not individual.

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