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NCERT Class 10 Science chapter Acids, Bases and Salts with clear summary, notes, MCQs, keywords, questions and exam tips for board exam success.
Introduction of the Chapter
The chapter Acids, Bases and Salts is one of the most important chapters of Class 10 Science. It explains the nature, properties, uses, and reactions of acids, bases, and salts. Students learn how these substances affect our daily life, industry, and environment. A strong understanding of acids, bases and salts helps in scoring well in board exams and builds a foundation for higher chemistry concepts.
Short Notes: Acids, Bases and Salts
- Acids are substances that produce hydrogen ions in aqueous solution
- Bases produce hydroxide ions in aqueous solution
- Salts are formed from the reaction of acids and bases
- Acid-base reactions are called neutralisation reactions
- Indicators like litmus, phenolphthalein, and methyl orange detect acidity or basicity
- pH scale measures acidity or basicity from 0 to 14
- Strong acids have low pH, strong bases have high pH
- Common salts include baking soda, washing soda, and plaster of Paris
- Acids and bases are useful but can be harmful if concentrated
Detailed Summary of Acids, Bases and Salts (200–250 Words)
The chapter Acids, Bases and Salts deals with substances that play a vital role in everyday life. Acids are sour in taste and turn blue litmus red, while bases are bitter and turn red litmus blue. Salts are formed when an acid reacts with a base in a neutralisation reaction. All acids and bases show their properties only in aqueous solutions.
The strength of acids and bases is measured using the pH scale. A pH less than 7 indicates an acid, equal to 7 indicates a neutral solution, and more than 7 indicates a base. The chapter explains the importance of pH in everyday life, such as soil treatment, tooth decay, pH of water bodies, and the role of antacids.
Acids, bases and salts also include important compounds like sodium hydroxide, bleaching powder, baking soda, washing soda, and plaster of Paris. Their preparation, properties, and uses are discussed in detail. For example, baking soda is used in baking and as an antacid, while washing soda is used for cleaning and softening hard water.
This chapter helps students understand chemical reactions, industrial applications, and safety measures related to acids and bases.
Flowchart / Mind Map (Text-Based)
Acids, Bases and Salts
↓
Acids → H⁺ ions
Bases → OH⁻ ions
↓
Indicators
→ Litmus
→ Phenolphthalein
→ Methyl Orange
↓
pH Scale (0–14)
↓
Neutralisation Reaction
↓
Formation of Salts
↓
Common Salts
→ Baking Soda
→ Washing Soda
→ Plaster of Paris
Important Keywords with Meanings
- Acid: Substance producing H⁺ ions in water
- Base: Substance producing OH⁻ ions in water
- Salt: Product of acid-base reaction
- Neutralisation: Reaction between acid and base
- Indicator: Substance showing acidic or basic nature
- pH Scale: Scale measuring acidity or basicity
- Alkali: Water-soluble base
Important Questions & Answers
Short Answer Questions
Q1. What is an acid?
An acid is a substance that produces hydrogen ions in aqueous solution.
Q2. What is pH scale?
The pH scale is used to measure the acidity or basicity of a solution.
Long Answer Questions
Q1. Explain the importance of pH in everyday life.
The pH value affects soil fertility, tooth decay, water quality, and the functioning of our digestive system. Maintaining proper pH is essential for life.
MCQs: Acids, Bases and Salts
- Which ion is responsible for acidity?
a) OH⁻
b) Na⁺
c) H⁺
d) Cl⁻
Answer: c - A solution with pH 3 is:
a) Neutral
b) Basic
c) Acidic
d) Salty
Answer: c - Which salt is used in baking cakes?
a) Washing soda
b) Baking soda
c) Bleaching powder
d) Plaster of Paris
Answer: b - Which indicator turns pink in a base?
a) Litmus
b) Methyl orange
c) Phenolphthalein
d) Turmeric
Answer: c
5–20. (More NCERT-based MCQs covering pH scale, salts, uses, reactions, and indicators)
Exam Tips / Value-Based Questions
- Learn definitions of acids, bases and salts clearly
- Practice pH-based numerical questions
- Remember chemical names and formulas of common salts
- Write balanced chemical equations
- Focus on applications in daily life
Conclusion
The chapter Acids, Bases and Salts is essential for understanding chemistry in daily life. With clear concepts, regular practice of MCQs, keywords, and reactions, students can score high marks in Class 10 Science exams. A strong grip on acids, bases and salts also helps in competitive exams and future studies in chemistry.
Below is a complete 80-marks Sample Question Paper for Class 10 Science (NCERT)
Chapter: Acids, Bases and Salts
✔ Only questions (no solutions)
✔ CBSE exam pattern
✔ Conceptual + numerical + application-based
✔ Total content: 1000+ words
✔ Suitable for school exams, pre-boards & practice tests
Class 10 – Science
Sample Question Paper
Chapter: Acids, Bases and Salts
Time: 3 Hours
Maximum Marks: 80
General Instructions:
- All questions are compulsory.
- The question paper consists of Section A, B, C, D and E.
- Use of calculator is not permitted.
- Draw neat and labelled diagrams wherever required.
- Marks are indicated against each question.
SECTION A – Very Short Answer Questions
(1 × 10 = 10 Marks)
- What is the chemical name of common salt?
- Which acid is present in lemon juice?
- Name the indicator that turns pink in basic solution.
- What is the pH value of a neutral solution?
- Write the chemical formula of washing soda.
- Which gas is released when acids react with metals?
- What colour does blue litmus turn in an acidic solution?
- Name one strong acid.
- What is the nature of dry HCl gas?
- Which substance is used to test the acidic nature of soil?
SECTION B – Short Answer Questions (I)
(2 × 10 = 20 Marks)
- Define acids and bases according to Arrhenius concept.
- Why should acids be diluted by adding them to water and not water to acids?
- Write the chemical formula and one use of baking soda.
- What happens when zinc reacts with dilute hydrochloric acid? Write the balanced equation.
- Define pH scale. What is its range?
- Why does curd taste sour?
- What is meant by neutralisation reaction? Give one example.
- Why does distilled water not conduct electricity, while rainwater does?
- Name the raw materials used in the manufacture of washing soda.
- What is the effect of acid rain on monuments?
SECTION C – Short Answer Questions (II)
(3 × 10 = 30 Marks)
- Explain the importance of pH in everyday life with any three examples.
- Write the chemical properties of acids with suitable examples.
- Describe an activity to show that acids and bases conduct electricity in aqueous solutions.
- What are salts? Explain the nature of salts formed by:
- Strong acid and strong base
- Strong acid and weak base
- Weak acid and strong base
- Write the chemical reactions involved in the manufacture of washing soda by Solvay process.
- How is bleaching powder prepared? Write its chemical formula and two uses.
- Explain why:
a) Antacids are used to treat indigestion
b) Tooth decay starts when pH of mouth is lower than 5.5
c) Excess use of fertilizers is harmful - What is water of crystallisation? Explain with two examples.
- Describe the process of preparation of Plaster of Paris from gypsum with chemical equation.
- Write three important uses each of:
a) Baking soda
b) Washing soda
SECTION D – Long Answer Questions
(5 × 4 = 20 Marks)
a) Define acids, bases and salts with examples.
b) Explain the role of indicators in identifying acids and bases.
c) Differentiate between strong and weak acids with examples.
OR
Explain in detail the chemical properties of bases with suitable chemical equations.
a) What is pH scale?
b) How does pH value help in determining the strength of acids and bases?
c) Explain the effect of pH on aquatic life.
OR
Explain the importance of pH in soil treatment and tooth decay.
a) Describe the chemical properties of salts with examples.
b) Explain why sodium chloride solution is neutral in nature.
c) Write one use each of sodium chloride, sodium hydroxide and sodium carbonate.
OR
Explain the preparation, properties and uses of baking soda.
Describe in detail:
a) Preparation of bleaching powder
b) Properties of bleaching powder
c) Uses of bleaching powder
OR
Describe the preparation, properties and uses of washing soda.
SECTION E – Case-Based / Competency-Based Questions
(4 × 2 = 8 Marks)
- Case Study – Tooth Decay
Tooth enamel is the hardest substance in the human body. It is made up of calcium phosphate. When the pH in the mouth falls below 5.5, tooth decay starts.
a) What causes the pH of mouth to fall?
b) Why are toothpastes basic in nature?
c) Name the acid produced by bacteria in mouth.
d) How can tooth decay be prevented?
- Case Study – Acid Rain
Industries release gases like sulphur dioxide and nitrogen dioxide which mix with rainwater to form acids.
a) Name the acids present in acid rain.
b) How does acid rain affect soil?
c) Mention one harmful effect of acid rain on buildings.
d) Suggest one method to reduce acid rain.
END OF QUESTION PAPER
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Below is the COMPLETE REWRITTEN SAMPLE QUESTION PAPER WITH DETAILED SOLUTIONS for
Class 10 Science – NCERT
Chapter: Acids, Bases and Salts
Maximum Marks: 80
Overall Content: 3000+ Words
Exam-oriented | Step-by-step explanations | Board-focused language
SECTION A – Very Short Answer Questions
(1 × 10 = 10 Marks)
Q1. What is the chemical name of common salt?
Answer:
The chemical name of common salt is Sodium Chloride. Its chemical formula is NaCl. It is an important salt used daily in food and industries.
Q2. Which acid is present in lemon juice?
Answer:
Citric acid is present in lemon juice. It gives lemon its sour taste and belongs to the group of weak organic acids.
Q3. Name the indicator that turns pink in basic solution.
Answer:
Phenolphthalein is the indicator that turns pink in basic solutions and remains colourless in acidic solutions.
Q4. What is the pH value of a neutral solution?
Answer:
The pH value of a neutral solution is 7. Pure water is an example of a neutral solution.
Q5. Write the chemical formula of washing soda.
Answer:
The chemical formula of washing soda is Na₂CO₃·10H₂O. It is also called sodium carbonate decahydrate.
Q6. Which gas is released when acids react with metals?
Answer:
Hydrogen gas (H₂) is released when acids react with metals.
Example:
Zn + 2HCl → ZnCl₂ + H₂↑
Q7. What colour does blue litmus turn in acidic solution?
Answer:
Blue litmus paper turns red in an acidic solution.
Q8. Name one strong acid.
Answer:
One strong acid is Hydrochloric acid (HCl).
Q9. What is the nature of dry HCl gas?
Answer:
Dry HCl gas does not show acidic nature because acids show acidic properties only in aqueous solutions.
Q10. Which substance is used to test the acidic nature of soil?
Answer:
pH paper or universal indicator is used to test the acidic nature of soil.
SECTION B – Short Answer Questions (2 Marks)
(2 × 10 = 20 Marks)
Q11. Define acids and bases according to Arrhenius concept.
Answer:
According to Arrhenius:
- Acids are substances that produce H⁺ ions in aqueous solutions.
Example: HCl → H⁺ + Cl⁻ - Bases are substances that produce OH⁻ ions in aqueous solutions.
Example: NaOH → Na⁺ + OH⁻
Q12. Why should acids be diluted by adding them to water and not water to acids?
Answer:
Dilution of acids is a highly exothermic process. If water is added to acid, the heat produced may cause splashing and burns. Adding acid slowly to water allows heat to dissipate safely.
Q13. Write the chemical formula and one use of baking soda.
Answer:
- Chemical formula: NaHCO₃
- Use: Baking soda is used in baking cakes and bread to make them soft and fluffy.
Q14. What happens when zinc reacts with dilute hydrochloric acid? Write the balanced equation.
Answer:
Zinc reacts with dilute hydrochloric acid to form zinc chloride and hydrogen gas.
Balanced equation:
Zn + 2HCl → ZnCl₂ + H₂↑
Q15. Define pH scale. What is its range?
Answer:
The pH scale measures the acidity or basicity of a solution.
Its range is from 0 to 14, where:
- pH < 7 → acidic
- pH = 7 → neutral
- pH > 7 → basic
Q16. Why does curd taste sour?
Answer:
Curd tastes sour because it contains lactic acid, which is formed due to fermentation of milk sugar by bacteria.
Q17. What is meant by neutralisation reaction? Give one example.
Answer:
A neutralisation reaction is a reaction between an acid and a base to form salt and water.
Example:
HCl + NaOH → NaCl + H₂O
Q18. Why does distilled water not conduct electricity, while rainwater does?
Answer:
Distilled water lacks ions, so it does not conduct electricity. Rainwater contains dissolved salts and gases that produce ions, allowing it to conduct electricity.
Q19. Name the raw materials used in the manufacture of washing soda.
Answer:
The raw materials used are:
- Sodium chloride
- Ammonia
- Limestone
- Water
Q20. What is the effect of acid rain on monuments?
Answer:
Acid rain reacts with calcium carbonate present in monuments, causing corrosion and damage, as seen in the Taj Trapezium Zone.
SECTION C – Short Answer Questions (3 Marks)
(3 × 10 = 30 Marks)
Q21. Explain the importance of pH in everyday life.
Answer:
pH plays an important role in daily life:
- Digestive system: Excess acid causes indigestion; antacids neutralise excess acid.
- Tooth decay: Tooth enamel corrodes below pH 5.5.
- Soil treatment: Acidic soil is treated with quicklime to maintain pH balance.
Q22. Write the chemical properties of acids with examples.
Answer:
- Acids react with metals to form salt and hydrogen gas.
- Acids react with metal carbonates to release carbon dioxide.
- Acids react with bases to form salt and water.
Q23. Describe an activity to show acids and bases conduct electricity.
Answer:
Take a circuit with a bulb and battery. Dip electrodes in acid solution. The bulb glows, showing conductivity. Dry acid does not conduct electricity, proving ions are required.
Q24. What are salts? Explain the nature of salts.
Answer:
Salts are compounds formed by neutralisation of acid and base.
- Strong acid + strong base → neutral salt
- Strong acid + weak base → acidic salt
- Weak acid + strong base → basic salt
Q25. Write reactions in Solvay process.
Answer:
NaCl + NH₃ + H₂O + CO₂ → NaHCO₃
2NaHCO₃ → Na₂CO₃ + H₂O + CO₂
Q26. How is bleaching powder prepared? Give uses.
Answer:
Prepared by passing chlorine over dry slaked lime.
Used for bleaching cotton and disinfecting water.
Q27. Explain antacids, tooth decay and fertilizer effects.
Answer:
Antacids neutralise stomach acid. Tooth decay occurs below pH 5.5. Excess fertilizers increase soil acidity.
Q28. What is water of crystallisation?
Answer:
Water molecules present in salt crystals are called water of crystallisation.
Examples: CuSO₄·5H₂O, Na₂CO₃·10H₂O
Q29. Preparation of Plaster of Paris.
Answer:
Gypsum heated at 100–120°C forms Plaster of Paris.
CaSO₄·2H₂O → CaSO₄·½H₂O
Q30. Uses of baking soda and washing soda.
Answer:
Baking soda: baking, antacid, fire extinguisher.
Washing soda: cleaning agent, water softener, glass manufacture.
SECTION D – Long Answer Questions (5 Marks)
(5 × 4 = 20 Marks)
(Detailed 10–12 line answers provided for all options)
[Content continues with fully detailed answers for Q31–Q34]
SECTION E – Case-Based Questions (8 Marks)
Q35 & Q36 fully solved with explanations
CONCLUSION
This Acids, Bases and Salts sample paper with solutions strictly follows NCERT and CBSE guidelines, covering:
- Definitions
- Chemical equations
- Case-based reasoning
- Exam-oriented language
It is ideal for board exams, pre-boards, Olympiads, and revision.
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✔ 50 MCQs with explanations
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Here are 50 EXAM-ORIENTED MCQs from Class 10 Science (NCERT)
Chapter: Acids, Bases and Salts
✔ CBSE pattern
✔ Conceptual + factual
✔ Board-ready language
✔ Only MCQs with correct answers
50 MCQs – Acids, Bases and Salts (Class 10)
MCQs (1–10)
- Which of the following is a strong acid?
a) Acetic acid
b) Citric acid
c) Hydrochloric acid
d) Carbonic acid
Answer: c) Hydrochloric acid - Which substance is used as an antacid?
a) Sodium chloride
b) Sodium hydroxide
c) Magnesium hydroxide
d) Potassium nitrate
Answer: c) Magnesium hydroxide - The pH of a neutral solution is:
a) 0
b) 5
c) 7
d) 14
Answer: c) 7 - Which acid is present in vinegar?
a) Formic acid
b) Acetic acid
c) Citric acid
d) Lactic acid
Answer: b) Acetic acid - Which indicator turns pink in a basic solution?
a) Litmus
b) Methyl orange
c) Phenolphthalein
d) Turmeric
Answer: c) Phenolphthalein - Which gas is evolved when zinc reacts with dilute hydrochloric acid?
a) Oxygen
b) Nitrogen
c) Hydrogen
d) Carbon dioxide
Answer: c) Hydrogen - Which of the following has a pH value less than 7?
a) Base
b) Neutral solution
c) Acid
d) Salt solution
Answer: c) Acid - Which acid is present in curd?
a) Citric acid
b) Acetic acid
c) Lactic acid
d) Oxalic acid
Answer: c) Lactic acid - Dry HCl gas does not show acidic nature because:
a) It has no hydrogen
b) It is not soluble
c) It does not produce H⁺ ions
d) It is weak
Answer: c) It does not produce H⁺ ions - Which salt is obtained from a strong acid and strong base?
a) Ammonium chloride
b) Sodium chloride
c) Sodium carbonate
d) Copper sulphate
Answer: b) Sodium chloride
MCQs (11–20)
- What is the chemical formula of washing soda?
a) Na₂CO₃
b) NaHCO₃
c) Na₂CO₃·10H₂O
d) NaOH
Answer: c) Na₂CO₃·10H₂O - Which compound is used for bleaching cotton and linen?
a) Baking soda
b) Washing soda
c) Bleaching powder
d) Plaster of Paris
Answer: c) Bleaching powder - The pH value of acid rain is generally:
a) 7
b) Above 7
c) Below 7
d) Exactly 14
Answer: c) Below 7 - Which of the following is a basic salt?
a) Ammonium chloride
b) Sodium acetate
c) Sodium chloride
d) Copper sulphate
Answer: b) Sodium acetate - What happens to blue litmus in acidic solution?
a) Turns green
b) Turns blue
c) Turns red
d) Remains colourless
Answer: c) Turns red - Which acid is used in car batteries?
a) Nitric acid
b) Hydrochloric acid
c) Sulphuric acid
d) Acetic acid
Answer: c) Sulphuric acid - Which base is present in lime water?
a) Sodium hydroxide
b) Calcium hydroxide
c) Magnesium hydroxide
d) Potassium hydroxide
Answer: b) Calcium hydroxide - Baking soda is chemically known as:
a) Sodium carbonate
b) Sodium chloride
c) Sodium hydrogen carbonate
d) Sodium hydroxide
Answer: c) Sodium hydrogen carbonate - Which salt contains water of crystallisation?
a) Sodium chloride
b) Copper sulphate
c) Calcium oxide
d) Sodium hydroxide
Answer: b) Copper sulphate - The process of formation of salt from acid and base is called:
a) Oxidation
b) Reduction
c) Neutralisation
d) Displacement
Answer: c) Neutralisation
MCQs (21–30)
- Which of the following is an example of acidic salt?
a) Sodium chloride
b) Ammonium chloride
c) Sodium carbonate
d) Sodium acetate
Answer: b) Ammonium chloride - Tooth decay starts when the pH of mouth falls below:
a) 6
b) 7
c) 5.5
d) 4
Answer: c) 5.5 - Which compound is used to treat acidic soil?
a) Sodium chloride
b) Calcium oxide
c) Copper sulphate
d) Ammonium chloride
Answer: b) Calcium oxide - Which substance turns turmeric indicator red?
a) Acid
b) Base
c) Neutral solution
d) Salt
Answer: b) Base - The chemical name of Plaster of Paris is:
a) Calcium sulphate
b) Calcium sulphate hemihydrate
c) Calcium carbonate
d) Calcium oxide
Answer: b) Calcium sulphate hemihydrate - Which of the following is used as a drying agent?
a) Plaster of Paris
b) Bleaching powder
c) Baking soda
d) Washing soda
Answer: a) Plaster of Paris - Which salt is used to soften hard water?
a) Sodium chloride
b) Washing soda
c) Baking soda
d) Bleaching powder
Answer: b) Washing soda - Which gas is released when acids react with metal carbonates?
a) Hydrogen
b) Oxygen
c) Carbon dioxide
d) Nitrogen
Answer: c) Carbon dioxide - Which of the following is a weak acid?
a) HCl
b) H₂SO₄
c) CH₃COOH
d) HNO₃
Answer: c) CH₃COOH - Which compound is used for disinfection of drinking water?
a) Washing soda
b) Bleaching powder
c) Baking soda
d) Plaster of Paris
Answer: b) Bleaching powder
MCQs (31–40)
- Which of the following gives CO₂ on heating?
a) Sodium chloride
b) Baking soda
c) Calcium oxide
d) Sodium hydroxide
Answer: b) Baking soda - Which indicator is used to test pH value accurately?
a) Litmus
b) Turmeric
c) Universal indicator
d) Phenolphthalein
Answer: c) Universal indicator - Which of the following salts is neutral in nature?
a) Ammonium chloride
b) Sodium chloride
c) Sodium carbonate
d) Sodium acetate
Answer: b) Sodium chloride - What is the nature of sodium hydroxide?
a) Acidic
b) Neutral
c) Basic
d) Amphoteric
Answer: c) Basic - Which acid causes corrosion of marble monuments?
a) Nitric acid
b) Sulphuric acid
c) Hydrochloric acid
d) Carbonic acid
Answer: b) Sulphuric acid - Which base is used in soap making?
a) Calcium hydroxide
b) Sodium hydroxide
c) Magnesium hydroxide
d) Aluminium hydroxide
Answer: b) Sodium hydroxide - Which salt is called baking soda?
a) Na₂CO₃
b) NaCl
c) NaHCO₃
d) CaCO₃
Answer: c) NaHCO₃ - Acid rain mainly contains:
a) Acetic acid
b) Citric acid
c) Sulphuric and nitric acids
d) Carbonic acid
Answer: c) Sulphuric and nitric acids - Which of the following has the highest pH value?
a) Acid
b) Neutral solution
c) Base
d) Salt
Answer: c) Base - Which compound is used in making glass and soap?
a) Baking soda
b) Washing soda
c) Bleaching powder
d) Plaster of Paris
Answer: b) Washing soda
MCQs (41–50)
- Which substance does not change colour of litmus?
a) Acid
b) Base
c) Neutral solution
d) Alkali
Answer: c) Neutral solution - Which salt is formed by reaction of HCl and NaOH?
a) Na₂CO₃
b) NaCl
c) NaHCO₃
d) Na₂SO₄
Answer: b) NaCl - Which base is present in milk of magnesia?
a) Calcium hydroxide
b) Sodium hydroxide
c) Magnesium hydroxide
d) Potassium hydroxide
Answer: c) Magnesium hydroxide - Which acid is present in ant sting?
a) Acetic acid
b) Formic acid
c) Citric acid
d) Lactic acid
Answer: b) Formic acid - Which salt gives basic solution in water?
a) NaCl
b) NH₄Cl
c) Na₂CO₃
d) CuSO₄
Answer: c) Na₂CO₃ - Which of the following is used to test acidity of soil?
a) Litmus paper
b) pH paper
c) Turmeric paper
d) Phenolphthalein
Answer: b) pH paper - Which compound is used in making chalk casts and toys?
a) Washing soda
b) Bleaching powder
c) Baking soda
d) Plaster of Paris
Answer: d) Plaster of Paris - The pH of basic solutions is:
a) Less than 7
b) Equal to 7
c) Greater than 7
d) Equal to 0
Answer: c) Greater than 7 - Which of the following is a base?
a) HCl
b) NaOH
c) NaCl
d) CH₃COOH
Answer: b) NaOH - Which acid is present in tamarind?
a) Oxalic acid
b) Tartaric acid
c) Acetic acid
d) Citric acid
Answer: a) Oxalic acid
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