Assertion: Sulphide ores are concentrated by the froth flotation method.

Reason: Cresols stabilise the froth in the froth flotation method.

1.  Both assertion and reason are true and the reason is the correct explanation of assertion.

2.  Both assertion and reason are true but the reason is not the correct explanation of assertion.

3.  Assertion is true but the reason is false.

4.  Assertion is false but the reason is true.

Hint: Method is used for removing gangue from sulphide ores.

Sulphide ores are concentrated by the froth floatation method. Sulphide ore particles are preferentially wetted by oil, become l
lighter and rise to the surface along with the froth while gangue particles are preferentially wetted by water become heavier and
thus settle down at the bottom of the tank and cresols stabilise the froth in the froth floatation method.

Formation of froth is main reason for extraction of metal. Metal ore comes out along with froth.