J.R. S. answered 04/26/21
Ph.D. University Professor with 10+ years Tutoring Experience
pH = -log [H+]
pH + pOH = 14
[H+][OH-] = 1x10-14
a). pH of 1x10-3 M HCl
HCl is a strong acid so ionizes completely producing 1x10-3 M H+
-log 1x10-3 = pH = 3
b). 6x10-9 M KOH
KOH is a strong base so dissociates completely producing 6x10-9 M OH-
-log 6x10-9 = pOH = 8.22
pH = 14 - pOH
pH = 5.78