Ncert Exercises & Solutions

Given below are two statements:

Assertion (A):	Sulphide ores are concentrated by the froth flotation method.
Reason (R):	Cresols stabilise the froth in the froth flotation method.

1.	Both (A) and (R) are true and (R) is the correct explanation of (A).
2.	Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.	(A) is true but (R) is false.
4.	(A) is false but (R) 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.