Science is one of the most scoring subjects in the CBSE Class 10 Board Examination, provided students understand the concepts thoroughly and practice regularly. At Dhingra Classes Nashik, we believe that solving Previous Year Questions (PYQs), Multiple Choice Questions (MCQs), Short Answer Questions, and Long Answer Questions is the key to mastering Science and scoring 95+ marks.

In this article, we provide a comprehensive set of solved PYQs, MCQs, short Q&A, and long Q&A based on Lesson 2: Acids, Bases and Salts from the CBSE Class 10 Science syllabus. This guide is designed to help students revise effectively and build confidence for the 2026 board examinations.

CBSE Class 10 Science – Lesson 2: Acids, Bases and Salts

Key Concepts Covered:

• Properties of acids and bases

• pH scale and its importance

• Types of salts and their uses

• Preparation and uses of common salts

• Neutralization reactions

• Importance of pH in everyday life

📌 Section A – Solved MCQs (Multiple Choice Questions)

1. The taste of an acid is:
(a) Bitter
(b) Sour
(c) Salty
(d) Sweet

✅ Answer: (b) Sour

2. Which of the following is a strong acid?
(a) Acetic acid
(b) Carbonic acid
(c) Hydrochloric acid
(d) Citric acid

✅ Answer: (c) Hydrochloric acid

3. The pH of a neutral solution is:
(a) 0
(b) 7
(c) 14
(d) 10

✅ Answer: (b) 7

4. Which gas is evolved when an acid reacts with a metal?
(a) Oxygen
(b) Nitrogen
(c) Hydrogen
(d) Carbon dioxide

✅ Answer: (c) Hydrogen

5. The chemical formula of washing soda is:
(a) Na₂CO₃
(b) Na₂CO₃·10H₂O
(c) NaHCO₃
(d) NaCl

✅ Answer: (b) Na₂CO₃·10H₂O

6. Which of the following is a strong base?
(a) Sodium hydroxide
(b) Ammonium hydroxide
(c) Calcium hydroxide
(d) Magnesium hydroxide

✅ Answer: (a) Sodium hydroxide

7. The pH of a solution with a high concentration of H⁺ ions is:
(a) High
(b) Low
(c) Neutral
(d) 7

✅ Answer: (b) Low

8. Which of the following salts is used in the preparation of soap?
(a) Sodium chloride
(b) Sodium carbonate
(c) Sodium hydroxide
(d) Sodium bicarbonate

✅ Answer: (c) Sodium hydroxide

9. The reaction between an acid and a base is called:
(a) Redox reaction
(b) Neutralization reaction
(c) Displacement reaction
(d) Decomposition reaction

✅ Answer: (b) Neutralization reaction

10. Which of the following is NOT a property of a base?
(a) Bitter taste
(b) Soapy touch
(c) Turns red litmus blue
(d) Turns blue litmus red

✅ Answer: (d) Turns blue litmus red

11. The pH of human blood is approximately:
(a) 4.5
(b) 6.5
(c) 7.4
(d) 8.5

✅ Answer: (c) 7.4

12. Which of the following is used as an antacid?
(a) Sodium chloride
(b) Sodium bicarbonate
(c) Sodium carbonate
(d) Sodium hydroxide

✅ Answer: (b) Sodium bicarbonate

13. The chemical formula of baking soda is:
(a) Na₂CO₃
(b) NaHCO₃
(c) NaCl
(d) NaOH

✅ Answer: (b) NaHCO₃

14. Which of the following acids is present in vinegar?
(a) Hydrochloric acid
(b) Sulphuric acid
(c) Acetic acid
(d) Citric acid

✅ Answer: (c) Acetic acid

15. When sodium hydroxide reacts with hydrochloric acid, the products are:
(a) NaCl and H₂O
(b) NaCl and H₂
(c) NaOH and H₂O
(d) HCl and H₂O

✅ Answer: (a) NaCl and H₂O

16. Which of the following is a weak acid?
(a) Hydrochloric acid
(b) Sulphuric acid
(c) Nitric acid
(d) Acetic acid

✅ Answer: (d) Acetic acid

17. The pH of a solution is 3. It is:
(a) Neutral
(b) Weakly acidic
(c) Strongly acidic
(d) Weakly basic

✅ Answer: (c) Strongly acidic

18. Which of the following is used in the manufacture of glass?
(a) Sodium chloride
(b) Sodium carbonate
(c) Sodium hydroxide
(d) Sodium bicarbonate

✅ Answer: (b) Sodium carbonate

19. Which of the following is a neutral salt?
(a) NaCl
(b) NaHCO₃
(c) Na₂CO₃
(d) NH₄Cl

✅ Answer: (a) NaCl

20. The acid present in tomato is:
(a) Acetic acid
(b) Citric acid
(c) Oxalic acid
(d) Lactic acid

✅ Answer: (c) Oxalic acid

21. Which of the following indicators is used to test acids and bases?
(a) Litmus paper
(b) Phenolphthalein
(c) Methyl orange
(d) All of the above

✅ Answer: (d) All of the above

22. The pH of a solution is 11. It is:
(a) Strongly acidic
(b) Weakly acidic
(c) Neutral
(d) Basic

✅ Answer: (d) Basic

23. Which of the following salts is used in making plaster of Paris?
(a) Sodium chloride
(b) Calcium carbonate
(c) Calcium sulphate hemihydrate
(d) Sodium carbonate

✅ Answer: (c) Calcium sulphate hemihydrate

24. The acid present in curd is:
(a) Acetic acid
(b) Lactic acid
(c) Citric acid
(d) Oxalic acid

✅ Answer: (b) Lactic acid

25. Which of the following is NOT a salt?
(a) NaCl
(b) NaHCO₃
(c) NaOH
(d) Na₂CO₃

✅ Answer: (c) NaOH

📌 Section B – Solved Short Answer Questions (2–3 Marks)

Q1. What is an acid? Give two examples.

Answer: An acid is a substance that releases hydrogen ions (H⁺) when dissolved in water. Acids are sour in taste and turn blue litmus paper red.
Examples: Hydrochloric acid (HCl), Sulphuric acid (H₂SO₄), Acetic acid (CH₃COOH).

Q2. What is a base? Give two examples.

Answer: A base is a substance that releases hydroxide ions (OH⁻) when dissolved in water. Bases are bitter in taste, soapy to touch, and turn red litmus paper blue.
Examples: Sodium hydroxide (NaOH), Calcium hydroxide (Ca(OH)₂).

Q3. What is a neutralization reaction? Give an example.

Answer: A neutralization reaction is a reaction in which an acid reacts with a base to form a salt and water.
Example: NaOH + HCl → NaCl + H₂O

Q4. Define pH. What does the pH scale range from?

Answer: pH is a measure of the concentration of hydrogen ions (H⁺) in a solution. The pH scale ranges from 0 to 14:

• pH < 7 → Acidic

• pH = 7 → Neutral

• pH > 7 → Basic

Q5. What is the difference between a strong acid and a weak acid?

Q6. Why does hydrochloric acid gas not turn dry litmus paper red?

Answer: Hydrochloric acid gas does not dissociate into ions in the absence of water. Since litmus paper requires ions to change colour, dry HCl gas does not turn dry litmus paper red.

Q7. What is the chemical formula of baking soda? How is it prepared?

Answer: The chemical formula of baking soda is NaHCO₃. It is prepared by passing carbon dioxide gas through a concentrated solution of sodium chloride saturated with ammonia.

Equation: NaCl + H₂O + CO₂ + NH₃ → NaHCO₃ + NH₄Cl

Q8. What is the chemical formula of washing soda? How is it prepared?

Answer: The chemical formula of washing soda is Na₂CO₃·10H₂O. It is prepared by heating baking soda (NaHCO₃) to form sodium carbonate, which then crystallizes with 10 molecules of water.

Equation: 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂

Q9. Why is the pH of a solution important in everyday life?

Answer: pH is important in everyday life because:

• It determines whether a solution is acidic, basic, or neutral.

• It affects biological processes (e.g., blood pH must be ~7.4).

• It is used in agriculture to determine soil suitability.

• It helps in digestion, with stomach acid having a pH of ~1.5–2.

Q10. What is the role of pH in digestion?

Answer: The pH of stomach acid is around 1.5–2, which is highly acidic. This acidity helps in the activation of pepsin, the enzyme that digests proteins. It also kills harmful bacteria present in food.

📌 Section C – Solved Long Answer Questions (5 Marks)

Q1. Explain the properties of acids and bases with examples.

Answer:

Properties of Acids:

1. Taste: Sour

2. Litmus Test: Turns blue litmus paper red.

3. Reaction with Metals: Reacts with metals to produce hydrogen gas.
   Example: Zn + H₂SO₄ → ZnSO₄ + H₂

4. Reaction with Carbonates: Reacts with carbonates to produce CO₂ gas.
   Example: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

5. Conductivity: Conducts electricity in aqueous solution.

Properties of Bases:

1. Taste: Bitter

2. Touch: Soapy

3. Litmus Test: Turns red litmus paper blue.

4. Reaction with Acids: Neutralizes acids to form salt and water.
   Example: NaOH + HCl → NaCl + H₂O

5. Conductivity: Conducts electricity in aqueous solution.

Q2. Explain the pH scale and its importance in everyday life.

Answer:

pH Scale: The pH scale ranges from 0 to 14 and measures the concentration of H⁺ ions in a solution.

• pH < 7 → Acidic

• pH = 7 → Neutral

• pH > 7 → Basic

Importance of pH in Everyday Life:

1. Soil pH: Determines which crops can grow.

2. Digestion: Stomach acid has a pH of ~1.5–2 for protein digestion.

3. Blood pH: Must be maintained at ~7.4 for normal bodily functions.

4. Tooth Decay: Acidic conditions cause tooth decay.

5. Aquatic Life: pH affects the survival of aquatic organisms.

Q3. Write the chemical formula, preparation, and uses of common salts:

Q4. What is the difference between baking soda and washing soda?

Q5. Explain the importance of pH in the human body.

Answer: pH is crucial in the human body for:

1. Digestion: Stomach acid (pH ~1.5–2) activates pepsin for protein digestion.

2. Blood pH: Maintained at ~7.4 for normal bodily functions.

3. Enzyme Activity: Enzymes work best at specific pH levels.

4. Tooth Health: Acidic conditions cause tooth decay.

5. Cellular Function: pH affects cellular metabolism and function.

📌 Section D – Solved Previous Year Questions (PYQs)

Q1. (PYQ 2023) What is the pH of a solution that turns blue litmus paper red?

Answer: The solution is acidic, so its pH is less than 7.

Q2. (PYQ 2022) What is the chemical name of baking soda? How is it obtained?

Answer: The chemical name of baking soda is sodium bicarbonate (NaHCO₃). It is obtained by passing carbon dioxide gas through a concentrated solution of sodium chloride saturated with ammonia.

Equation: NaCl + H₂O + CO₂ + NH₃ → NaHCO₃ + NH₄Cl

Q3. (PYQ 2021) Why does the pH of a solution decrease when an acid is added to it?

Answer: When an acid is added to a solution, the concentration of H⁺ ions increases, which lowers the pH of the solution.

Q4. (PYQ 2020) Write the balanced chemical equation for the reaction between sodium hydroxide and hydrochloric acid. What type of reaction is it?

Answer:
Equation: NaOH + HCl → NaCl + H₂O
Type: Neutralization reaction

How Dhingra Classes Helps Students Master Science

At Dhingra Classes Nashik, we provide:

• Conceptual learning – Building strong fundamentals in Physics, Chemistry, and Biology.

• Regular practice – Worksheets, PYQs, MCQs, and mock tests.

• Doubt-clearing sessions – Instant clarification of queries.

• Personalized feedback – Identifying weak areas and providing targeted support.

Contact Dhingra Classes

• Phone: 98230 62106

• Email: dhingraclassesnsk@gmail.com

• Website: www.dhingraclassesnashik.com

• Address: Plot No 3, XQ3G+H3M Deacon Homes, 301C, opp. Metro Zone, near Guru Govind Sing, Samarth Nagar, Dnyaneshwar Nagar, Pathardi Phata, Nashik, Maharashtra 422009

Conclusion

Mastering Science Lesson 2: Acids, Bases and Salts requires a thorough understanding of concepts and consistent practice of PYQs, MCQs, short Q&A, and long Q&A. By solving these questions, students can build confidence and score high marks in the CBSE Class 10 board examinations.

At Dhingra Classes Nashik, we are committed to helping students achieve academic excellence through expert guidance and structured practice. Join us and embark on your journey to success!