Hey, Class 10 students! Welcome to your ultimate guide for Chapter 2: Acids, Bases, and Salts from the NCERT Science syllabus. This chapter is super interesting because it’s all about stuff we see every day—like lemon juice, soap, and even stomach acid! Whether you’re prepping for exams or just curious, we’ll break down all the key questions and answers in a simple way. Let’s dive into the world of acids, bases, and salts!
What Are Acids, Bases, and Salts?
- Acids: Sour-tasting substances that turn blue litmus red. Examples: Lemon juice (citric acid), vinegar (acetic acid).
- Bases: Bitter-tasting, slippery substances that turn red litmus blue. Examples: Soap (sodium hydroxide), baking soda.
- Salts: Formed when acids and bases react. Example: Table salt (NaCl).
These three are the stars of Chapter 2, and they’re everywhere in life—let’s explore them with questions!
Key Questions and Answers from Chapter 2
Here’s a list of important questions from Acids, Bases, and Salts with clear, easy answers:
Q1: What are the properties of acids?
Answer:
Acids have these traits:
- Taste sour (don’t try this in the lab!).
- Turn blue litmus red.
- Release H⁺ ions in water (e.g., HCl → H⁺ + Cl⁻).
- React with metals to produce hydrogen gas (e.g., Zn + 2HCl → ZnCl₂ + H₂).
- Conduct electricity in water because of ions.
Example: Lemon juice stings a cut because it’s acidic!
Q2: What are the properties of bases?
Answer:
Bases are the opposites of acids:
- Taste bitter (again, no tasting!).
- Feel slippery (like soap).
- Turn red litmus blue.
- Release OH⁻ ions in water (e.g., NaOH → Na⁺ + OH⁻).
- Conduct electricity in solution.
Example: Soap feels slippery because it’s a base.
Q3: What is an indicator? Name three natural indicators.
Answer:
An indicator is a substance that changes color to show if something is acidic or basic.
Three natural indicators:
- Litmus: Red in acid, blue in base, purple when neutral.
- Turmeric: Yellow in acid/neutral, reddish-brown in base.
- Red Cabbage: Red in acid, blue/green in base.
Fun Fact: You can test these at home with lemon juice and soap water!
Q4: What is the pH scale? How does it work?
Answer:
The pH scale measures how acidic or basic a solution is, from 0 to 14:
- 0-6: Acidic (lower pH = stronger acid).
- 7: Neutral (like pure water).
- 8-14: Basic (higher pH = stronger base).
Example: Lemon juice has a pH of about 2 (acidic), while soap is around 10 (basic).
Tip: pH = “power of Hydrogen” because it’s about H⁺ ions!
Q5: What happens when an acid reacts with a metal? Give an example.
Answer:
Acids react with metals to produce a salt and hydrogen gas.
Example: Zinc + Hydrochloric Acid → Zinc Chloride + Hydrogen.
Equation: Zn + 2HCl → ZnCl₂ + H₂.
You’ll see bubbles of H₂ gas in the lab—pretty cool!
Q6: What is neutralization? Write a reaction.
Answer:
Neutralization is when an acid and a base react to form a salt and water.
Example: Hydrochloric Acid + Sodium Hydroxide → Sodium Chloride + Water.
Equation: HCl + NaOH → NaCl + H₂O.
Real Life: Antacids (bases) neutralize stomach acid (HCl) when you have acidity.
Q7: How are salts formed? Give an example.
Answer:
Salts form when an acid reacts with a base or a metal.
Example: Sulfuric Acid + Sodium Hydroxide → Sodium Sulfate + Water.
Equation: H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O.
Fact: Table salt (NaCl) comes from HCl and NaOH!
Q8: What is the difference between strong and weak acids?
Answer:
- Strong Acids: Fully break into ions in water (e.g., HCl, H₂SO₄). Very reactive!
- Weak Acids: Only partly break into ions (e.g., acetic acid in vinegar). Less reactive.
Example: HCl is strong and stings more than vinegar (weak).
Q9: What are the uses of acids, bases, and salts in daily life?
Answer:
- Acids: Citric acid in fruits, sulfuric acid in car batteries.
- Bases: Sodium hydroxide in soap, ammonia in cleaners.
- Salts: NaCl for cooking, baking soda (NaHCO₃) for baking.
Activity: Check your kitchen—spot acids (vinegar) and salts (table salt)!
Q10: What is the reaction when an acid reacts with a carbonate?
Answer:
Acid + Carbonate → Salt + Water + Carbon Dioxide.
Example: Hydrochloric Acid + Calcium Carbonate → Calcium Chloride + Water + CO₂.
Equation: 2HCl + CaCO₃ → CaCl₂ + H₂O + CO₂.
Sign: You’ll see fizzing from CO₂ gas!
Q11: Explain the reaction of acids with metal oxides.
Answer:
Acid + Metal Oxide → Salt + Water.
Example: Hydrochloric Acid + Copper Oxide → Copper Chloride + Water.
Equation: 2HCl + CuO → CuCl₂ + H₂O.
Note: Metal oxides are basic, so this is like neutralization.
Q12: What is water of crystallization? Give an example.
Answer:
Water of crystallization is water trapped in the structure of some salts.
Example: Copper Sulfate (CuSO₄·5H₂O) has 5 water molecules. When heated, it loses water and turns white from blue.
Equation: CuSO₄·5H₂O → CuSO₄ + 5H₂O.
Lab Tip: Try heating washing soda crystals—they do this too!
Q13: What are the chemical properties of salts?
Answer:
- Neutral salts (e.g., NaCl) don’t change pH.
- Acidic salts (e.g., NH₄Cl) come from strong acids + weak bases.
- Basic salts (e.g., Na₂CO₃) come from strong bases + weak acids.
Test: Dissolve in water and check with litmus!
Q14: Why does tooth decay happen? How is it linked to pH?
Answer:
Bacteria in your mouth turn sugar into acids, lowering the pH below 5.5. This acid eats away tooth enamel. Brushing with basic toothpaste (pH > 7) neutralizes it.
Tip: Less sugar = healthier teeth!
Q15: What is the importance of pH in soil?
Answer:
Plants grow best at a specific pH (usually 6-7). Too acidic (low pH)? Add lime (CaO). Too basic (high pH)? Add sulfur. Farmers test soil pH to boost crops!
Extra Questions from NCERT Exercises
- Name a salt used in black-and-white photography.
Answer: Silver chloride (AgCl)—it reacts to light. - What gas is produced when dilute HCl reacts with NaHCO₃?
Answer: Carbon dioxide (CO₂).
Equation: HCl + NaHCO₃ → NaCl + H₂O + CO₂. - Why do acids not show acidic behavior without water?
Answer: Acids need water to release H⁺ ions. Dry HCl gas doesn’t affect litmus, but wet HCl does!
Tips to Ace Chapter 2
- Learn Reactions: Memorize equations like HCl + NaOH → NaCl + H₂O.
- Understand pH: Practice using the scale with examples (e.g., milk = 6, soap = 10).
- Test Indicators: Know how litmus, turmeric, and phenolphthalein (pink in base) work.
- Revise Salts: Focus on common ones like NaCl, CuSO₄, and their uses.
- Practice Diagrams: Draw setups for reactions (e.g., H₂ gas test with Zn + HCl).
Chapter 2: Acids, Bases, and Salts is packed with cool science that’s all around us—from the sourness of lemons to the cleaning power of soap. With these questions and answers, you’re ready to tackle your Class 10 exams! Keep practicing, stay curious, and you’ll score big. Got doubts? Drop them below—I’m here to help. Happy studying, Science champs!
Class 10 Science Chapter 3: Metals and Non-Metals – Questions and Answers Explained Simply
Class 10 Science Chapter 4: Carbon and Its Compounds – Questions and Answers Made Easy
Class 10 Science Chapter 5: Periodic Classification of Elements – Questions and Answers Simplified
Class 10 Science Chapter 6: Life Processes – Questions and Answers Explained Simply