Q. 19. What role does adsorption play in heterogeneous catalysis ? Q. 20. An ore sample of galena (PbS) is contaminated with zinc blende (ZnS). Name one chemical which an be used to concentrate galena...

Q. 19.
What role does adsorption play in heterogeneous catalysis ?

Q. 20.
An ore sample of galena (PbS) is contaminated with zinc blende (ZnS). Name one chemical which an be used to concentrate galena selectively by froth floatation method.

Q. 21.
When is electrolytic reduction applied for getting a metal ?

Q. 22.
Name the method that is used for refining of nickel.