Question

Assertion: Magnesium can reduce Al₂O₃ at a temperature below 1350°C while above 1350°C aluminium can reduce MgO.

Reason: The melting and boiling points of magnesium are lower than those of aluminium.

Options

• If both Assertion and Reason are CORRECT and Reason is the CORRECT explanation of the Assertion.

• If both Assertion and Reason are CORRECT but Reason is not the CORRECT explanation of the Assertion.

• If Assertion is CORRECT but Reason is INCORRECT.

• If Assertion is INCORRECT but Reason is CORRECT.

Answer 1

If Assertion is INCORRECT but Reason is CORRECT.

Explanation:

The assertion is correct because, according to the Ellingham diagram, at temperatures below 1350°C, magnesium can reduce Al₂O₃, while above 1350°C, aluminium can reduce MgO. The reason is incorrect because this behaviour depends on thermodynamic stability (ΔG° values) of oxides, not on melting or boiling points of the metals. The change in feasibility is due to the crossing of Ellingham lines for MgO and Al₂O₃ around 1350°C.