A process employed for the concentration of a sulphide ore is:A. Froth floatationB. Gravity separationC. Froth separationD. Gravity floatation

The correct answer is A. Froth flotation.

Explanation:
Froth flotation is a common method used to concentrate sulphide ores. In this process, the ore is mixed with water and certain chemicals, which make the sulphide particles hydrophobic (i.e., they repel water but attract air bubbles). Air is then bubbled through the mixture, causing the sulphide ore particles to attach to the air bubbles. These bubbles rise to the surface and form a froth, which is skimmed off, while the gangue (impurities) remains in the water.

Other options:

B. Gravity separation: This method is used for ores that have a significant difference in density between the ore and the gangue, but it's not suitable for sulphide ores.
C. Froth separation: This is not a valid technique in mineral processing.
D. Gravity floatation: This is also not a valid technique in mineral processing.
Thus, froth flotation is the correct method for concentrating sulphide ores.