This comprehensive guide we covers Acid Bases And Salts Class 10 Questions And Answers, extra questions, and most-asked conceptual doubts from CBSE Class 10 Science Chapter 2. Perfect for board exam prep, concept clarity, and competitive exams like NTSE & Olympiads.
Acid Bases And Salts Class 10 Questions And Answers
Page 18 – Litmus Test Identification
Q: You have three test tubes: one with distilled water, one with acid, one with base. Only red litmus paper is available. How will you identify each?
A:
- Acid: No change in red litmus
- Base: Turns red litmus blue
- Neutral (water): No effect on either litmus
Page 22 – Reaction with Metals
Q: Which gas is released when acid reacts with metal? How is it tested?
A: Hydrogen gas is released. It burns with a pop sound when tested with a burning matchstick.
Q: Why should curd not be stored in copper/brass vessels?
A: Acids in curd react with metal, forming toxic compounds that can cause food poisoning.
Page 25 – Acidic Nature & Ionization
Q: Why do HCl and HNO₃ show acidic character in water, but glucose and alcohol don’t?
A: Because HCl/HNO₃ ionize to release H⁺ ions in water. Glucose and alcohol do not ionize.
Q: Why does dry HCl gas not change dry litmus paper color?
A: No ionization occurs without water, so no H⁺ ions are released.
Page 28 – pH & Soil Treatment
Q: pH of solution A is 6, B is 8. Which is acidic?
A: A is acidic (more H⁺ ions), B is basic.
Q: When is soil treated with quicklime or chalk?
A: When soil is too acidic (low pH), to neutralize it.
Page 33 – Salts & Applications
Q: Common name of CaOCl₂?
A: Bleaching powder
Q: Sodium compound used to soften hard water?
A: Sodium carbonate (Na₂CO₃)
Q: Reaction of Plaster of Paris with water?
A: CaSO₄·½H₂O + 1½H₂O → CaSO₄·2H₂O
NCERT Exercise Questions
Q: A solution turns red litmus blue. Its pH is likely:
A: 10 (basic)
Q: Which gas turns lime water milky when reacting with eggshells?
A: CO₂ (from HCl + CaCO₃)
Q: Which medicine treats indigestion?
A: Antacid
Q: Balanced equation: HCl + Zn → ?
A: Zn + 2HCl → ZnCl₂ + H₂↑
Extra Questions (Most Searched)
Q: What is the role of pH in tooth decay?
A: Below pH 5.5, enamel starts corroding due to acid from bacteria.
Q: Why is baking soda used as an antacid?
A: It neutralizes excess stomach acid (NaHCO₃ is basic).
Q: What is the difference between strong and weak acids?
A: Strong acids ionize completely (HCl), weak acids partially (CH₃COOH).
Q: Why is acid added to water and not vice versa?
A: To prevent splashing due to exothermic reaction.
Read More Human Eye Class 10 Questions and Answers
Additional Important Questions & Answers – Class 10 Science Chapter 2
🧪 Conceptual & Application-Based Questions
Q: What is the nature of metal oxides and non-metal oxides?
A:
- Metal oxides are generally basic (e.g., Na₂O, MgO).
- Non-metal oxides are generally acidic (e.g., CO₂, SO₂).
- Exception: Some oxides like Al₂O₃ are amphoteric (react with both acids and bases).
Q: What are olfactory indicators? Give examples.
A: Substances that change their smell in acidic or basic media.
- Examples: Onion, vanilla, clove
- Onion loses smell in base, retains in acid.
Q: What is the chemical name and formula of baking soda?
A:
- Name: Sodium hydrogen carbonate
- Formula: NaHCO₃
Q: What is the chlor-alkali process?
A: Electrolysis of brine (NaCl solution) to produce:
- Chlorine (Cl₂)
- Hydrogen (H₂)
- Sodium hydroxide (NaOH)
Q: Why does acid rain damage buildings and soil?
A: Acid rain (pH < 5.6) contains sulfuric and nitric acids, which:
- Corrode marble (CaCO₃)
- Lower soil pH, harming crops
Q: What is the role of pH in agriculture?
A:
- Acidic soil (low pH): Treated with quicklime or chalk
- Basic soil (high pH): Treated with organic matter or gypsum
Q: Why is tooth enamel affected by acidic food?
A: Enamel corrodes below pH 5.5, leading to tooth decay.
Q: What is the difference between neutralization and displacement reactions?
A:
- Neutralization: Acid + Base → Salt + Water
- Displacement: Metal + Acid → Salt + Hydrogen gas
Q: What is water of crystallization?
A: Fixed number of water molecules in a salt’s crystal structure.
- Example: CuSO₄·5H₂O (blue vitriol)
Q: Which salt is used to remove permanent hardness of water?
A: Washing soda (Na₂CO₃·10H₂O)
🧠 Assertion & Reason Type (CBSE Pattern)
Assertion: While diluting acid, always add acid to water.
Reason: The reaction is highly exothermic and can cause splashing. Answer: Both A and R are true, and R explains A.
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🧪 Real-Life Applications
| Compound | Use Case |
|---|---|
| Bleaching Powder | Disinfection, water treatment |
| Baking Soda (NaHCO₃) | Antacid, fire extinguisher |
| Washing Soda (Na₂CO₃) | Softening hard water |
| Plaster of Paris | Bone setting, sculptures |
