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Practice Class 9 Science Chapter 2 – Is Matter Around Us Pure? with 5 NCERT-based MCQs on mixtures, compounds, physical properties, chemical properties, separation methods and the differences between pure substances and mixtures.
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Chapter Information
Subject: Science
Class: 9
Chapter: Is Matter Around Us Pure?
Question Type: Multiple Choice Questions (MCQs)
Practice Set: 8
Difficulty Level: Moderate
Based On: NCERT Syllabus
Introduction
Matter around us can be classified as pure substances and mixtures. Pure substances have a fixed composition and include elements and compounds, while mixtures contain two or more substances that are physically combined.
Different mixtures can be separated using suitable physical methods depending on the properties of their components.
This Practice Set 8 focuses on physical and chemical properties, pure substances, mixtures and suitable methods used for separating mixtures.
What You Will Learn
✔ Physical properties of substances
✔ Chemical properties of substances
✔ Pure substances
✔ Mixtures
✔ Separation of mixtures
✔ Difference between physical and chemical properties
✔ Selection of suitable separation methods
Why This Topic Is Important
Understanding physical and chemical properties helps students identify substances and distinguish different types of changes.
Knowledge of separation methods is also important because mixtures can often be separated into their components using differences in physical properties such as boiling point, solubility and particle size.
These concepts are useful for both conceptual and application-based examination questions.
5 MCQs with Answers and Detailed Solutions
Q1. Which of the following is a physical property of a substance?
A) Ability to burn
B) Reactivity with oxygen
C) Melting point
D) Reaction with acids
Answer: C) Melting point
Detailed Solution
A physical property can be observed or measured without changing the chemical identity of the substance.
Examples include:
- Melting point
- Boiling point
- Density
- Colour
- Solubility
The ability to burn and reactions with oxygen or acids are chemical properties because they involve chemical reactions.
Exam Tip
If a property can be observed without forming a new substance, it is generally a physical property.
Q2. Which of the following is a chemical property?
A) Density
B) Boiling point
C) Colour
D) Reactivity with oxygen
Answer: D) Reactivity with oxygen
Detailed Solution
A chemical property describes how a substance behaves during a chemical reaction.
The reactivity of a substance with oxygen indicates its ability to undergo a chemical reaction with oxygen.
Density, boiling point and colour are physical properties.
Exam Tip
Reactivity = Chemical property is an important relationship to remember.
Q3. Which method is most suitable for separating two miscible liquids having sufficiently different boiling points?
A) Filtration
B) Distillation
C) Handpicking
D) Sedimentation
Answer: B) Distillation
Detailed Solution
Distillation can be used to separate components of a mixture of liquids when they have different boiling points.
The liquid with the lower boiling point vaporises first and can then be condensed and collected separately.
Filtration is mainly used for separating an insoluble solid from a liquid.
Exam Tip
For a mixture of miscible liquids with different boiling points, think of distillation.
Q4. Which method can be used to separate a mixture of sand and water?
A) Filtration
B) Distillation only
C) Sublimation
D) Chromatography
Answer: A) Filtration
Detailed Solution
Sand is an insoluble solid in water.
When sand and water are passed through a suitable filter, the sand particles are retained by the filter paper while water passes through.
Therefore, filtration is an appropriate method for separating sand from water.
Exam Tip
Insoluble solid + liquid → Filtration is a useful rule for basic separation questions.
Q5. Which statement correctly describes a pure substance?
A) It always contains two or more substances.
B) It has a fixed composition and characteristic properties.
C) Its components can always be separated by filtration.
D) Its composition changes from sample to sample.
Answer: B) It has a fixed composition and characteristic properties.
Detailed Solution
A pure substance has a fixed composition and characteristic properties.
Elements and compounds are classified as pure substances.
A mixture can have variable composition because its components may be present in different proportions.
Exam Tip
Remember: Pure substance → fixed composition.
Important Formulas & Concepts
This topic mainly involves conceptual understanding rather than mathematical formulas.
1. Physical Property
A property that can be observed or measured without changing the chemical identity of a substance.
Examples: Colour, density, melting point and boiling point.
2. Chemical Property
A property that describes the ability of a substance to undergo a chemical reaction.
Examples: Reactivity with oxygen and acids.
3. Pure Substance
A substance having a fixed composition and characteristic properties.
4. Mixture
A combination of two or more substances in which the components are physically combined.
5. Filtration
Used to separate an insoluble solid from a liquid.
Example: Sand and water.
6. Distillation
Used to separate liquids based on differences in their boiling points.
Related Practice Questions
Q1. What is a physical property?
Q2. What is a chemical property?
Q3. What is a pure substance?
Q4. When is filtration used?
Q5. What is the principle behind distillation?
Mini Quiz Challenge
Try answering these questions within 60 seconds.
Q1. Which is a physical property?
A) Burning
B) Reactivity with acid
C) Boiling point
D) Rusting
Q2. Which is a chemical property?
A) Density
B) Colour
C) Melting point
D) Reactivity with oxygen
Q3. Which method is suitable for separating sand from water?
A) Filtration
B) Distillation
C) Sublimation
D) Chromatography
Q4. Which method is commonly used to separate miscible liquids having different boiling points?
A) Filtration
B) Distillation
C) Sedimentation
D) Handpicking
Q5. A pure substance has:
A) Variable composition
B) Fixed composition
C) Only liquid components
D) Only solid components
Exam Tips
✔ Learn the difference between physical and chemical properties.
✔ Remember that a pure substance has a fixed composition.
✔ Choose separation methods according to the physical properties of the components.
✔ Remember sand + water → filtration.
✔ Remember miscible liquids with different boiling points → distillation.
Quick Revision Notes
✔ Physical property: Can be observed without changing chemical identity.
✔ Chemical property: Describes chemical reactivity.
✔ Pure substance: Has fixed composition.
✔ Mixture: Contains two or more physically combined substances.
✔ Filtration: Separates insoluble solid from liquid.
✔ Distillation: Separates liquids based on differences in boiling points.
✔ Melting point: Physical property.
✔ Reactivity with oxygen: Chemical property.
Common Mistakes Students Make
❌ Confusing physical properties with chemical properties.
❌ Thinking a pure substance can have a variable composition.
❌ Using filtration to separate dissolved salt from water.
❌ Choosing filtration for a mixture of two miscible liquids.
❌ Forgetting that separation methods depend on differences in physical properties.
Key Takeaways
✔ Physical properties can be observed without changing the chemical identity of a substance.
✔ Chemical properties describe how substances undergo chemical reactions.
✔ Pure substances have fixed composition.
✔ Mixtures contain physically combined substances.
✔ Filtration is useful for separating insoluble solids from liquids.
✔ Distillation can separate miscible liquids based on differences in boiling points.
FAQs
Q. What is a physical property?
Answer:
A physical property is a property that can be observed or measured without changing the chemical identity of a substance.
Q. What is a chemical property?
Answer:
A chemical property describes the ability of a substance to undergo a chemical reaction.
Q. What is a pure substance?
Answer:
A pure substance has a fixed composition and characteristic properties.
Q. How can sand be separated from water?
Answer:
Sand can be separated from water by filtration because sand is insoluble in water.
Q. Which method is used to separate miscible liquids with different boiling points?
Answer:
Distillation can be used to separate such liquids.
Conclusion
Class 9 Science Chapter 2 – Is Matter Around Us Pure? focuses on physical and chemical properties, pure substances, mixtures and separation methods.
Understanding the properties of substances and selecting a suitable separation technique according to those properties is important for mastering this chapter and solving examination-based MCQs.
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