NCERT Class 10 Science Science: Chapter 2 — Acids, Bases and Salts
This chapter, Acids, Bases and Salts, from NCERT Class 10 Science, introduces students to the fundamental concepts of acids and bases. It revisits the familiar tastes of sour (acids) and bitter (bases) substances and explains their neutralizing effect on each other, a property used in remedies for acidity. The chapter highlights natural indicators like litmus and turmeric, explaining how they change colour in acidic and basic solutions, using the example of curry stains on cloth. It also mentions synthetic indicators such as phenolphthalein and methyl orange. The text introduces olfactory indicators, whose odour changes in acidic or basic media, and outlines laboratory activities to test various acids and bases using these indicators. This foundational knowledge is crucial for understanding chemical reactions and their applications in daily life, supporting the CBSE curriculum.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 10 |
| Subject | Science |
| Book | Science |
| Chapter | Chapter 2 — Acids, Bases and Salts |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 693 |
Learning outcomes
- Understand the properties of acids and bases.
- Identify natural and synthetic indicators.
- Explain the concept of neutralization.
- Differentiate between acidic, basic, and neutral solutions.
- Recognize the use of acids, bases, and salts in daily life.
Vocabulary
| Word | Meaning |
|---|---|
| Acids | Substances that are sour in taste and turn blue litmus red. |
| Bases | Substances that are bitter and turn red litmus blue. |
| Litmus | A natural indicator extracted from lichen, which is purple in neutral solution. |
| Indicator | A substance that indicates the presence of an acid or base by a change in colour or odour. |
| Turmeric | A natural indicator that turns reddish-brown in basic solutions. |
| Phenolphthalein | A synthetic indicator used to test for acids and bases. |
| Methyl orange | A synthetic indicator used to test for acids and bases. |
| Olfactory indicators | Substances whose odour changes in acidic or basic media. |
| Neutralization | The reaction between an acid and a base to form salt and water. |
| Hydrochloric acid | A common strong acid (HCl). |
| Sodium hydroxide | A common strong base (NaOH). |
| Distilled water | Pure water without any dissolved minerals or impurities. |
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Practice questions
- What is the taste of acids and bases? Answer: Acids are sour in taste, while bases are bitter in taste.
- How does blue litmus paper behave in an acidic solution? Answer: Blue litmus paper turns red in an acidic solution.
- Name two natural indicators. Answer: Litmus and turmeric are two natural indicators.
- What is the effect of soap on a turmeric stain? Answer: Soap, being basic, turns a turmeric stain reddish-brown.
- What are olfactory indicators? Answer: Olfactory indicators are substances whose odour changes in acidic or basic media.
Frequently asked questions
What is the main difference between acids and bases?
Acids are typically sour and turn blue litmus red, while bases are bitter and turn red litmus blue.
What is litmus and how is it used?
Litmus is a natural indicator extracted from lichen. It is purple in neutral solutions, red in acidic solutions, and blue in basic solutions.
Can turmeric be used as an indicator? How?
Yes, turmeric is a natural indicator. It remains yellow in acidic and neutral solutions but turns reddish-brown in basic solutions.
What are synthetic indicators?
Synthetic indicators are man-made substances like phenolphthalein and methyl orange that change colour to indicate whether a solution is acidic or basic.
What is the purpose of Activity 2.1 in the chapter?
Activity 2.1 demonstrates how to test various acids and bases in the laboratory using different indicators like litmus, phenolphthalein, and methyl orange.
What are olfactory indicators?
Olfactory indicators are substances whose smell changes in acidic or basic conditions, such as onions or vanilla essence.
Related resources
Important topics
Topics covered
NCERT Class 10 Science — Science — Chapter 2 — Acids, Bases and Salts. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.