Question

20. How does Roasting differ from Calcination? Give equations.
21. State the factors on which resistance of a conductor depends
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Answer 1

Calcination it is the process of heating and ore in the absence of air

Roasting it is the process of heating and or in the presence of air

Calcination process is usually e for the carbonate ores whereas roasting process is usually e for the sulphide ores.

The factors on which the resistance of a conductor depends are as follows

1. It depends on temperature

2. It depends on the area of cross section of the wire

3. It depends on the length of the conductor or wire

4. It depends on the nature of the material.

Answer 2

Roasting is the process in which the ore is heated below its melting point in presence of air to oxidise the impurities. Calcination is the process of heating the ore below its melting point an absence of air to remove volatile impurities like arsenic etc.

21. Resistance of a conductor depends upon:-

1). length of wire

2). Area of cross section of the wire

3). Temperature of wire

4). Nature of material of the wire.