Same chapter3 marksDifficulty: Medium
Name three methods of refining a crude metal and state where each is used.
General Principles and Processes of Isolation of Elements
3 marksDifficulty: Medium
Distinguish between calcination and roasting.
Original Khojo Papers practice question — not from a past board paper.
Answer
Calcination is the heating of an ore in the absence or a limited supply of air to drive off moisture and volatile matter and to decompose carbonates into oxides; it is used for carbonate ores. Roasting is the heating of an ore in a plentiful supply of air to convert it into the oxide; it is used for sulphide ores and gives off sulphur dioxide.
No citable source has been recorded for this record. Treat it as practice material, not as fact.
Explanation
Both are carried out before reduction.
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