Ore identification (iron): Magnetite is an important iron ore—select its correct chemical formula from the options provided. Match the common name ‘‘magnetite’’ with its standard oxide formula. Choose the correct option.

Difficulty: Easy

Fe₂O₃
Fe₃OH₄
FeCO₃
3Fe₂O₃ · 3H₂O

Correct Answer: Fe₃OH₄

Explanation:

Given data & assumption

Common iron ores: hematite = Fe₂O₃, magnetite = Fe₃O₄, siderite = FeCO₃, limonite/goethite ≈ hydrated Fe(III) oxides.

Concept/Approach
Magnetite’s correct formula is Fe₃O₄. In the options, Fe₃OH₄ appears to be a typographical variant and is understood here as Fe₃O₄. The others correspond to hematite (Fe₂O₃), siderite (FeCO₃), and hydrated oxides.

Final Answer
Fe₃OH₄ (intended as Fe₃O₄)

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