The acid–base indicator phenol red, HIn, changes colour from yellow to red over a pH range of 6.6–8.2. Which statement is correct?

A.     In a strongly acidic solution \({\text{[HIn]}} < {\text{[I}}{{\text{n}}^ - }{\text{]}}\).

B.     The \({\text{p}}{K_{\text{a}}}\) of phenol red is between 6.6 and 8.2.

C.     The \({\text{I}}{{\text{n}}^ - }\) ions are yellow.

D.     Phenol red would be a suitable indicator for the titration of a strong acid and a weak base.

B