A student added phenolphthalein to a solution, and it became pink. What is the nature of the solution?
Answer and explanation
Correct answer: Basic
Phenolphthalein is an acid-base indicator. It is colourless in acidic and neutral conditions, but it develops a pink colour in a basic solution, especially when the pH is sufficiently alkaline. The observed pink colour therefore indicates that the solution is basic, making option A correct. Acidity would keep the indicator colourless, and being a salt alone does not determine the observed colour without knowing its solution properties.
Frequently asked questions
What is the correct answer to this question?
Basic
Why is this the correct answer?
Phenolphthalein is an acid-base indicator. It is colourless in acidic and neutral conditions, but it develops a pink colour in a basic solution, especially when the pH is sufficiently alkaline. The observed pink colour therefore indicates that the solution is basic, making option A correct. Acidity would keep the indicator colourless, and being a salt alone does not determine the observed colour without knowing its solution properties.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
