Wrong shortcode initialized

 

I. Chapter Summary

This chapter introduces the fundamental concepts of acids, bases, and salts through their physical and chemical properties, uses, and reactions. Students learn how to identify acids and bases using indicators, the pH scale, and understand neutralization reactions. It also covers the preparation and uses of important salts like sodium chloride, baking soda, washing soda, and bleaching powder. The role of acids and bases in daily life and industries is emphasized through real-world examples.

II. Key Concepts Covered

Concept	Description
Acids	Substances that produce H⁺ ions in aqueous solutions (e.g., HCl, H₂SO₄).
Bases	Substances that produce OH⁻ ions in aqueous solutions (e.g., NaOH, NH₄OH).
Indicators	Substances that show a color change in acidic or basic solutions (e.g., litmus, phenolphthalein, methyl orange).
pH Scale	Measures the hydrogen ion concentration; ranges from 0 (acidic) to 14 (basic).
Neutralization Reaction	Reaction between an acid and a base to form salt and water.
Common Salts	NaCl (table salt), NaHCO₃ (baking soda), CaOCl₂ (bleaching powder), Na₂CO₃ (washing soda).
Acid Rain	Formed by reaction of acidic oxides (SO₂, NO₂) with water; harmful to life and buildings.
Uses of Salts	Domestic, industrial, and medical applications of salts and their derivatives.

III. Important Questions

(A) Multiple Choice Questions (1 Mark)

1. Which of the following gives a pink color with phenolphthalein?
   a) HCl
   b) NaOH ✅ (PYQ 2020)
   c) CH₃COOH
   d) Lemon juice
2. Which one of the following is an example of a neutral salt?
   a) NaCl ✅
   b) Na₂CO₃
   c) NH₄Cl
   d) CH₃COONa
3. Which acid is present in vinegar?
   a) Citric acid
   b) Lactic acid
   c) Acetic acid ✅
   d) Oxalic acid
4. Which of the following substances is basic in nature?
   a) Lemon juice
   b) Milk of magnesia ✅
   c) Curd
   d) Vinegar

(B) Short Answer Questions (2/3 Marks)

1. Why do HCl and HNO₃ show acidic character in aqueous solutions, while alcohol and glucose do not? (PYQ 2019)
2. What is meant by a neutralization reaction? Give one example.
3. Write the chemical formulae and uses of baking soda and washing soda.
4. Why should curd and sour substances not be kept in brass or copper vessels?

(C) Long Answer Questions (5 Marks)

1. Define acids and bases. Give two examples of each from daily life. How can we identify them using indicators?
2. What is pH? How does the pH of soil and water affect life? Mention one example of industrial use of the pH scale.
3. Explain the preparation, chemical formula, and two uses each of:
   a) Baking soda
   b) Washing soda
   c) Bleaching powder
4. Describe an activity to show that acids produce hydrogen ions only in aqueous solution. What is the role of water in acid-base reactions? (PYQ 2021)

(D) HOTS (Higher Order Thinking Skills)

1. Why do basic solutions become less alkaline when CO₂ is passed through them? Explain with a balanced chemical equation.
2. In case of a bee sting (acidic), baking soda is applied. But in case of a wasp sting (alkaline), vinegar is applied. Explain why with a scientific reason.

IV. Key Formulas/Concepts

Concept	Formula/Reaction
Baking Soda	NaHCO₃ (Sodium bicarbonate)
Preparation: NaCl + H₂O + CO₂ + NH₃ → NH₄Cl + NaHCO₃
Washing Soda	Na₂CO₃·10H₂O (Sodium carbonate decahydrate)
Preparation: Na₂CO₃ + 10H₂O → Na₂CO₃·10H₂O
Bleaching Powder	CaOCl₂
Preparation: Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O
Neutralization	HCl + NaOH → NaCl + H₂O
pH	pH = –log[H⁺]
(pH < 7 → Acidic, pH = 7 → Neutral, pH > 7 → Basic)

V. Deleted Portions (CBSE 2025–2026)

 No portions have been deleted from this chapter as per the rationalized NCERT textbooks.

VI. Chapter-Wise Marks Bifurcation (Estimated – CBSE 2025–2026)

Unit/Chapter	Estimated Marks	Type of Questions Typically Asked
Chapter 2: Acids, Bases and Salts	6–8 Marks	1 Long Answer, 1–2 Short Answers, 1–2 MCQs

VII. Previous Year Questions (PYQs)

Year	Marks	Question
2021	5	Explain preparation and uses of baking soda, washing soda, and bleaching powder.
2020	1	Which substance gives pink color with phenolphthalein? (NaOH)
2019	2	Why do HCl and HNO₃ show acidic character in aqueous solution while glucose does not?
2018	3	Write the chemical formula and one use of baking soda.

VIII. Real-World Application Examples

Concept	Application
pH Scale	Soil testing in agriculture, determining acidity of water bodies.
Bleaching Powder	Disinfection of drinking water.
Baking Soda	Baking industry, antacids, fire extinguishers.
Acid-Base Reactions	Neutralizing acids in stomach, removing sting effects.
Salts	Industrial uses (glass, soap, textiles), food preservation.

IX. Student Tips & Strategies for Success

Time Management

• Study one salt or reaction every day for 10 minutes.
• Use a concept map to link acids, bases, indicators, and salts.

Exam Preparation

• Practice writing chemical equations clearly.
• Revise color changes of indicators with different acids/bases.
• Solve past year questions and sample papers.

Stress Management

• Practice reactions using color-coded notes or flashcards.
• Discuss and debate HOTS questions with peers to strengthen understanding.

X. Career Guidance & Exploration (Class-Specific)

For Classes 9–10

Academic Stream Options

• Science: Chemistry, Biochemistry, Environmental Science
• Commerce: Product Testing, Quality Control
• Arts: Science Journalism, Policy Research

Career Paths

• Pharmacist, Chemical Engineer, Water Quality Analyst, Lab Technician, Food Chemist

Competitive Exams

• NTSE, Junior Science Olympiad, Science Talent Search, NSO (National Science Olympiad)

XI. Important Notes

• Always refer to https://ncert.nic.in and https://cbseacademic.nic.in for latest syllabus and updates.
• Understanding basic reactions, pH, and salt usage is key to scoring well.
• Learn to classify acids/bases/salts based on strength, use, and pH.
• Revise indicator reactions frequently using real-life samples (e.g., lemon, soap).