The Indicator Propyl Red Has K_a = 3

Multiple Choice

The indicator propyl red has K_a = 3.3 × 10⁻⁶. What would be the approximate pH range over which it would change color?

A) 3.5−5.5
B) 4.5−6.5
C) 5.5−7.5
D) 6.5−8.5
E) None of these choices are correct.