4.
Which of the following equations correctly interrelates [ H
+
] and [ OH
-
] ?
a) [ H
+
] + [ OH
-
] = K
w
b) [ H
+
] + [ OH
-
] = 14
c) [ H
+
] * [ OH
-
] = K
w
d) [ H
+
] / [ OH
-
] = K
w
