What are the differences between calcination and roasting?

Chapter No. 8: Metallurgy,

What are the differences between calcination and roasting?

Ans.

Calcination	Roasting
This method is preferred for carbonate ores.	This method is preferred for sulphide ores.
In this method, ores are heated in limited supply of air.	In this method, ores are heated in excess of air.
During calcination, generally carbon dioxide gas is evolved.	During roasting, generally sulphur dioxide gas is evolved.
In this method, carbonate ores decompose to form metal oxide. E.g. ZnCO3 → ZnO + CO2 ↑	In this method, sulphide ores are oxidized to form metal oxides. E.g. 2ZnS + 3O2 → 2ZnO + 2SO2 ↑

What are the differences between metals and nonmetals. (On the basis of their physical properties)?

Chapter No. 8: Metallurgy,

What are the differences between metals and nonmetals. (On the basis of their physical properties)?

Ans.

Metals	Nonmetals
They are ductile and malleable.	They are brittle. (Except diamond)
They are good conductors of heat and electricity.	They are bad conductors of heat and electricity. (Except graphite)
They are lustrous.	They are non-lustrous. [Except iodine, diamond]
They have high melting and boiling points. (Except sodium, potassium, mercury, gallium)	They generally have low melting and boiling points.