(i) using collectors.
(ii) adjusting the proportion of oil to water.
(iii) using depressant.
(iv) using froth stabilisers.
Correct Answers:
(ii) adjusting the proportion of oil to water.
(iii) using depressant.
Explanation: In the Froth Floatation process, zinc sulphide and lead sulphide can be separated by adjusting the proportion of oil to water and by using depressant.