Mr ChemCoach Digital Lab – Universal Indicator

Class 10 | Acids, Bases and Salts | Interactive Virtual Lab + Quiz
Universal Indicator
A mixture of indicators that shows
different colours at different pH values.
Solution: pH 7 (Neutral)
Use pH buttons or pick an acid/base below to see how the
universal indicator colour and solution nature change.
Glowing pH Scale (0 – 14)
Strong Acid Neutral (7) Strong Base
Acids and Bases
Concept & Observation

A universal indicator is a mixture of dyes that shows different colours at different pH values. It is used to quickly identify whether a solution is strongly acidic, weakly acidic, neutral, weakly basic or strongly basic.

  • pH < 7 → Acidic solution (more H⁺ ions).
  • pH = 7 → Neutral solution (pure water).
  • pH > 7 → Basic solution (more OH⁻ ions).

In Class 10 CBSE, you study how different indicators like litmus, phenolphthalein and methyl orange work. The universal indicator gives a full colour scale (0–14), so it is more informative.

CBSE Class 10 | Acids, Bases and Salts
Virtual Lab | Mr ChemCoach
Student Quiz – Universal Indicator & pH
1. A solution turns universal indicator red. What can you say about the solution?
✅ Correct answer: Strong acid (Red indicates pH ~1–2).
2. Distilled water shows green colour with universal indicator. Its pH is:
✅ Correct answer: 7 (Neutral).
3. Which of the following will have a pH value more than 7?
✅ Correct answer: Soap solution (basic, pH > 7).
4. A solution shows purple colour with universal indicator. This indicates:
✅ Correct answer: Strong base. Purple/violet indicates very high pH.