+1 vote
in Fermentation Technology by (72.1k points)
Which of the following dye is colourless at acidic pH and becomes red at basic pH?

(a) Methyl red

(b) Thymol blue

(c) Phenolphthalein

(d) Phenol red

The question was posed to me in an online interview.

Origin of the question is Isolation and Screening of Industrially Important Microbes topic in division The Isolation, Preservation and Improvement of Industrial Microorganisms of Fermentation Technology

1 Answer

+2 votes
by (424k points)
selected by
 
Best answer
Correct option is (c) Phenolphthalein

Explanation: Phenolphthalein has a pH range between 8.0 – 10.0. It is colourless at pH 8.0 and becomes red at pH above 10.0. It belongs to the phthalein family that is employed as an acid-base indicator.

Related questions

We welcome you to Carrieradda QnA with open heart. Our small community of enthusiastic learners are very helpful and supportive. Here on this platform you can ask questions and receive answers from other members of the community. We also monitor posted questions and answers periodically to maintain the quality and integrity of the platform. Hope you will join our beautiful community
...