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Practice Class 10 Science Chapter 2 – Acids, Bases and Salts with 5 NCERT-based MCQs on acids, bases, indicators, chemical properties and reactions of acids with metals and bases.
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Chapter Information
Subject: Science
Class: 10
Chapter: Acids, Bases and Salts
Question Type: Multiple Choice Questions (MCQs)
Practice Set: 1
Difficulty Level: Moderate
Based On: NCERT Syllabus
Introduction
Acids, Bases and Salts is an important chapter in Class 10 Science. Acids and bases are commonly found in our daily lives and have many important chemical properties.
Acids generally produce hydrogen ions (H⁺) in aqueous solutions, while bases produce hydroxide ions (OH⁻) in aqueous solutions. Their properties can be identified using indicators such as litmus, methyl orange and phenolphthalein.
This Practice Set 1 focuses on the basic concepts of acids and bases, indicators, and important chemical reactions of acids.
What You Will Learn
✔ Properties of acids
✔ Properties of bases
✔ Indicators
✔ Litmus test
✔ Reactions of acids with metals
✔ Formation of hydrogen gas
✔ Reactions between acids and bases
✔ Basic chemical concepts related to acids and bases
Why This Topic Is Important
Understanding the basic properties of acids and bases is essential for studying the remaining concepts of this chapter.
Questions based on indicators, reactions of acids with metals, neutralisation and identification of acidic or basic substances are important for school examinations and competitive practice.
Students should understand not only the definitions but also how acids and bases behave during chemical reactions.
5 MCQs with Answers and Detailed Solutions
Q1. Which of the following substances turns blue litmus paper red?
A) Sodium hydroxide solution
B) Hydrochloric acid
C) Calcium hydroxide solution
D) Baking soda solution
Answer: B) Hydrochloric acid
Detailed Solution
Hydrochloric acid (HCl) is an acid. Acids change the colour of blue litmus paper to red.
On the other hand, bases generally turn red litmus blue.
Therefore, hydrochloric acid will turn blue litmus paper red.
Hence, the correct answer is B.
Exam Tip
Remember:
Acid → Blue litmus → Red
Base → Red litmus → Blue
Q2. When an acid reacts with a metal, which gas is generally produced?
A) Oxygen
B) Nitrogen
C) Hydrogen
D) Carbon dioxide
Answer: C) Hydrogen
Detailed Solution
Many acids react with certain metals to produce a salt and hydrogen gas.
For example:
Zn + 2HCl → ZnCl₂ + H₂
Here, zinc reacts with hydrochloric acid to form zinc chloride and hydrogen gas.
The evolution of hydrogen gas can be tested by bringing a burning matchstick near the gas. Hydrogen burns with a characteristic pop sound.
Therefore, the correct answer is C) Hydrogen.
Exam Tip
Remember the general reaction:
Acid + Metal → Salt + Hydrogen gas
Q3. Which of the following is a natural indicator?
A) Litmus
B) Sodium chloride
C) Hydrochloric acid
D) Sodium hydroxide
Answer: A) Litmus
Detailed Solution
Litmus is a natural indicator obtained from organisms called lichens.
It is used to identify whether a substance is acidic or basic.
- Acidic solution → Blue litmus turns red
- Basic solution → Red litmus turns blue
Sodium chloride is a salt, while hydrochloric acid and sodium hydroxide are an acid and a base respectively.
Therefore, the correct answer is A) Litmus.
Exam Tip
Litmus → Natural indicator
It is commonly used to distinguish acids from bases.
Q4. What type of reaction occurs when hydrochloric acid reacts with sodium hydroxide?
A) Oxidation reaction
B) Neutralisation reaction
C) Decomposition reaction
D) Displacement reaction
Answer: B) Neutralisation reaction
Detailed Solution
Hydrochloric acid (HCl) is an acid and sodium hydroxide (NaOH) is a base.
When an acid reacts with a base, they form salt and water. This reaction is called a neutralisation reaction.
The reaction is:
HCl + NaOH → NaCl + H₂O
Here:
- HCl = Hydrochloric acid
- NaOH = Sodium hydroxide
- NaCl = Sodium chloride
- H₂O = Water
Therefore, the correct answer is B) Neutralisation reaction.
Exam Tip
Remember:
Acid + Base → Salt + Water
This is called neutralisation.
Q5. Which of the following correctly represents the reaction of an acid with a metal carbonate?
A) Acid + Metal carbonate → Salt + Water + Carbon dioxide
B) Acid + Metal carbonate → Salt + Hydrogen
C) Acid + Metal carbonate → Metal oxide + Water
D) Acid + Metal carbonate → Only water
Answer: A) Acid + Metal carbonate → Salt + Water + Carbon dioxide
Detailed Solution
Acids react with metal carbonates to produce a salt, water and carbon dioxide gas.
For example, hydrochloric acid reacts with sodium carbonate:
2HCl + Na₂CO₃ → 2NaCl + H₂O + CO₂
The carbon dioxide gas produced can be identified because it turns lime water milky.
Therefore, the correct answer is A.
Exam Tip
Remember this important reaction:
Acid + Metal Carbonate → Salt + Water + CO₂
Important Concepts
1. Acids
Acids are substances that produce H⁺ ions in aqueous solution.
Examples include:
- Hydrochloric acid — HCl
- Sulphuric acid — H₂SO₄
- Nitric acid — HNO₃
Acids generally have a sour taste, although laboratory chemicals should never be tasted.
2. Bases
Bases are substances that produce OH⁻ ions in aqueous solution.
Examples include:
- Sodium hydroxide — NaOH
- Potassium hydroxide — KOH
- Calcium hydroxide — Ca(OH)₂
Bases generally show basic properties and can change the colour of indicators.
3. Indicators
Indicators are substances that help identify whether a solution is acidic or basic by showing a colour change.
Common indicators include:
- Litmus
- Methyl orange
- Phenolphthalein
Litmus
Acid → Blue litmus turns red
Base → Red litmus turns blue
4. Reaction of Acids with Metals
Many acids react with metals to produce salt and hydrogen gas.
Acid + Metal → Salt + Hydrogen
Example:
Zn + 2HCl → ZnCl₂ + H₂
5. Reaction of Acids with Metal Carbonates
Acids react with metal carbonates to produce salt, water and carbon dioxide.
Acid + Metal Carbonate → Salt + Water + Carbon dioxide
Example:
2HCl + Na₂CO₃ → 2NaCl + H₂O + CO₂
6. Neutralisation Reaction
When an acid reacts with a base, salt and water are generally formed.
Acid + Base → Salt + Water
Example:
HCl + NaOH → NaCl + H₂O
This reaction is called neutralisation.
Related Practice Questions
Q1. What happens when blue litmus paper is placed in an acidic solution?
Q2. Which gas is evolved when zinc reacts with hydrochloric acid?
Q3. What is a neutralisation reaction?
Q4. What are indicators?
Q5. What products are formed when an acid reacts with a metal carbonate?
Mini Quiz Challenge
Try answering these questions within 60 seconds.
Q1. Which colour does blue litmus turn in an acidic solution?
A) Blue
B) Red
C) Green
D) Yellow
Q2. Which gas is produced when an acid reacts with a suitable metal?
A) Oxygen
B) Hydrogen
C) Carbon dioxide
D) Nitrogen
Q3. Which of the following is a base?
A) HCl
B) H₂SO₄
C) NaOH
D) HNO₃
Q4. What is formed when HCl reacts with NaOH?
A) NaCl and H₂O
B) H₂ and O₂
C) CO₂ and H₂O
D) Na₂CO₃ and H₂
Q5. Which gas is produced when an acid reacts with a metal carbonate?
A) Hydrogen
B) Oxygen
C) Carbon dioxide
D) Nitrogen
Exam Tips
✔ Remember the colour changes of litmus.
✔ Learn the reaction of acids with metals.
✔ Remember that hydrogen gas is produced when many acids react with suitable metals.
✔ Learn the general reaction of acids with metal carbonates.
✔ Remember Acid + Base → Salt + Water.
✔ Understand the difference between acids, bases and indicators.
✔ Practise chemical equations along with their word equations.
Quick Revision Notes
✔ Acid: Produces H⁺ ions in aqueous solution.
✔ Base: Produces OH⁻ ions in aqueous solution.
✔ Indicator: Shows a characteristic colour change in acidic or basic medium.
✔ Litmus: A natural indicator.
✔ Acid + Metal → Salt + Hydrogen
✔ Acid + Metal Carbonate → Salt + Water + Carbon dioxide
✔ Acid + Base → Salt + Water
✔ Neutralisation: Reaction between an acid and a base producing salt and water.
Common Mistakes Students Make
❌ Confusing acids with bases.
❌ Forgetting that blue litmus turns red in an acidic solution.
❌ Writing oxygen instead of hydrogen for the reaction of an acid with a suitable metal.
❌ Forgetting carbon dioxide in the reaction between an acid and a metal carbonate.
❌ Confusing neutralisation with other types of chemical reactions.
❌ Not balancing chemical equations properly.
Key Takeaways
✔ Acids and bases have different chemical properties.
✔ Indicators are useful for identifying acidic and basic solutions.
✔ Litmus is a natural indicator.
✔ Acids react with suitable metals to produce hydrogen gas.
✔ Acids react with metal carbonates to produce carbon dioxide.
✔ Acids react with bases in neutralisation reactions.
✔ Chemical equations help represent these reactions clearly.
FAQs
Q. What happens when an acid reacts with a metal?
Answer:
Many acids react with suitable metals to form a salt and hydrogen gas.
Q. What is a neutralisation reaction?
Answer:
The reaction between an acid and a base that produces salt and water is called a neutralisation reaction.
Q. What happens to blue litmus in an acidic solution?
Answer:
Blue litmus turns red in an acidic solution.
Q. Which gas is produced when an acid reacts with a metal carbonate?
Answer:
Carbon dioxide (CO₂) is produced.
Q. What is litmus?
Answer:
Litmus is a natural indicator obtained from lichens and is used to identify acidic and basic solutions.
Conclusion
Class 10 Science Chapter 2 – Acids, Bases and Salts introduces the fundamental concepts of acids, bases and indicators. It also covers important reactions of acids with metals, metal carbonates and bases.
A clear understanding of these basic reactions will help students solve more advanced questions related to pH, salts, common salt, baking soda, washing soda, bleaching powder and other important compounds in the upcoming practice sets.
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