Roasting differs from calcination because roasting is done
AIn the presence of excess air
BIn a sealed vacuum container
COnly in cold water solution
DOnly at low room temperature
Answer & Solution
Correct answer: A. In the presence of excess air
1. Sulphide ores need oxygen to convert to oxide.
2. Roasting is heating in excess air for that purpose.
3. Calcination, in contrast, uses no air.
4. Hence option A is correct.
_Source: Selina Concise Chemistry Class 10, Ch 7 Metallurgy (Mistral OCR'd PDF), section on roasting_
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