A solution gives green colour with universal indicator. When a small amount of acid is added, the colour becomes yellow. What does this show?
Answer and explanation
Correct answer: The solution became slightly acidic
The governing concept is the colour scale of a universal indicator. Green generally corresponds to a nearly neutral solution around pH 7, while yellow indicates a lower pH and therefore mild acidity. Adding acid increases the hydrogen-ion concentration and shifts the pH below neutral, producing the yellow colour. Hence option B is correct. The solution did not become more basic, remain unchanged, or turn solid, so A, C, and D do not fit the observation.
Frequently asked questions
What is the correct answer to this question?
The solution became slightly acidic
Why is this the correct answer?
The governing concept is the colour scale of a universal indicator. Green generally corresponds to a nearly neutral solution around pH 7, while yellow indicates a lower pH and therefore mild acidity. Adding acid increases the hydrogen-ion concentration and shifts the pH below neutral, producing the yellow colour. Hence option B is correct. The solution did not become more basic, remain unchanged, or turn solid, so A, C, and D do not fit the observation.
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.
