The most important ore of aluminium is

Analyze the question: You're asked to identify the main ore from which aluminium is extracted.

Explain the concept: An ore is a naturally occurring mineral from which a metal can be extracted economically. Aluminium is the most abundant metal in the Earth's crust, but it is always found combined with other elements. Its main commercial ore is bauxite, which is hydrated aluminium oxide, Al₂O₃·2H₂O.

Check each option:

• A. Bauxite: Al₂O₃·2H₂O. This is the main ore of aluminium. ✔
• B. Haematite: Fe₂O₃. This is an ore of iron.
• C. Magnetite: Fe₃O₄. This is also an ore of iron.
• D. Monazite: a phosphate mineral of rare earth elements and thorium (not aluminium).

How aluminium is extracted:

1. Bauxite is purified to get pure alumina (Al₂O₃) using the Bayer process.
2. The alumina is dissolved in molten cryolite (Na₃AlF₆), which lowers the melting point.
3. The mixture is electrolysed (the Hall-Héroult process) with carbon electrodes, and aluminium collects at the cathode.

Answer: The correct option is A. bauxite.

Exam tip: Match the ore with its metal using these:

• Bauxite → Aluminium
• Haematite and Magnetite → Iron (both are iron oxides)
• Cassiterite → Tin
• Galena → Lead
• Zinc blende → Zinc