8. Why do frother reagents lie on the liquid surface of bubbles? a. Higher surface tension b. Water repellent c. More elastic 9. What type of modifier reagent is used to facilitate selective flotation? a. Regulator b. Activator c. Depressor d. b+c e. All of the above f. None of the above 10. What type of modifier reagent controls pulp alkalinity? a. Regulator b. Activator c. Depressor d. b+c e. All of the above