Assertion (A): The extraction of metals from their sulphide ores cannot take place without roasting of the ore.

Reason (R): Roasting converts sulphide ores directly into metals.

Assertion (A) is true because extracting a metal directly from its sulphide ore is highly difficult and thermodynamically unfavorable. It is much easier to reduce a metal oxide to its metallic form. Therefore, sulphide ores must undergo roasting (heating strongly in the presence of excess air) to be converted into metal oxides first. Reason (R) is false because roasting does not convert sulphide ores directly into metals; instead, it converts them into metal oxides (for example, $2ZnS + 3O_2 \rightarrow 2ZnO + 2SO_2$). These metal oxides must then be reduced using a reducing agent like carbon to obtain the free metal.