Matter in Our Surroundings — NCERT Solutions | Class 9 Science | Academia Aeternum
Ch 2  ·  Q–
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Class 9 Science Exercise NCERT Solutions Olympiad Board Exam
Chapter 2

Matter in Our Surroundings

Step-by-step NCERT solutions with stress–strain analysis and exam-oriented hints for Boards, JEE & NEET.

11 Questions
25–35 min Ideal time
Q1 Now at
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Q1
NUMERIC3 marks
Which separation techniques will you apply for the separation of the following?
  1. Sodium chloride from its solution in water
  2. Ammonium chloride from a mixture containing sodium chloride and ammonium chloride
  3. Small pieces of metal in the engine oil of a car
  4. Different pigments from an extract of flower petals
  5. Butter from curd
  6. Oil from water
  7. Tea leaves from tea
  8. Iron pins from sand
  9. Wheat grains from husk
  10. Fine mud particles suspended in water
📘 Concept & Theory Concept Builder ›

Separation of mixtures is one of the most important applications of the physical properties of matter. Different substances in a mixture possess different characteristics such as particle size, density, solubility, magnetic nature, boiling point, sublimation tendency, and miscibility. These differences are utilized to separate the components of a mixture.

Before selecting a separation technique, we should identify:

  • Whether the mixture is homogeneous or heterogeneous.
  • Whether the components are solids, liquids, or gases.
  • Whether one component is soluble or insoluble in another.
  • Whether the substances differ in density, magnetic properties, or volatility.
🗺️ Solution Roadmap Step-by-step Plan ›

  1. Identify the type of mixture.

  2. Determine the physical property that differs among the components.

  3. Select the separation technique based on that property.

  4. Justify why the chosen method is the most suitable.

📊 Graph / Figure Graph / Figure ›
METHODS OF SEPARATION OF MIXTURESSOLID - SOLIDPROPERTYMETHODMagnetismMagnetic SeparationSublimationSublimationParticle SizeSievingSOLID - LIQUIDPROPERTYMETHODInsolubleFiltrationDensitySedimentationVolatilityEvaporationSolubilityCrystallizationLIQUID - LIQUIDPROPERTYMETHODDensitySep. FunnelBoiling Pt.DistillationAdsorptionChromatog.
Methods of Separation
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  40 steps
  1. a. Sodium chloride from its solution in water
  2. Identify the mixture.
    Sodium chloride is dissolved in water, forming a homogeneous solution.
  3. Observe the difference in properties.
    Water is volatile and can evaporate, whereas sodium chloride is non-volatile.
  4. Select the separation method.
    Evaporation or Crystallization can be used.
  5. Perform the separation.
    Water is heated and evaporates, leaving behind sodium chloride crystals.
  6. b. Ammonium chloride from a mixture containing sodium chloride and ammonium chloride
  7. Identify the components.
    The mixture contains sodium chloride and ammonium chloride.
  8. Observe the physical property difference.
    Ammonium chloride undergoes sublimation, whereas sodium chloride does not.
  9. Select the separation method.
    Sublimation is the most suitable technique.
  10. Perform the separation.
    On heating, ammonium chloride changes directly intovapours. These vapours are cooled and collected as solid ammonium chloride, while sodium chloride remains behind.
    Answer: Sublimation.
  11. c. Small pieces of metal in the engine oil of a car
  12. Identify the mixture.
    Metal particles are suspended in liquid engine oil.
  13. Observe the difference in physical state and particle size.
    The metal pieces are solid impurities present in a liquid.
  14. Select the separation method.
    Filtration is suitable. If the particles are iron-based, magnetic separation may also be used.
  15. Perform the separation.
    The oil is passed through a filter that traps metal particles.
    Answer: Filtration (or Magnetic Separation if the metal is magnetic).
  16. d. Different pigments from an extract of flower petals
  17. Identify the mixture.
    Flower extract contains several coloured pigments.
  18. Observe the property difference.
    Different pigments move at different rates through an absorbent medium.
  19. Select the separation method.
    Chromatography is used.
  20. Perform the separation.
    The pigments travel different distances on chromatographic paper and get separated into distinct bands.
    Answer: Chromatography.
  21. e. Butter from curd
  22. Identify the mixture.
    Curd contains fat globules dispersed in liquid.
  23. Observe the density difference.
    Fat particles are lighter than the liquid portion.
  24. Select the separation method.
    Churning (centrifugation principle) is used.
  25. Perform the separation.
    Churning causes fat globules to come together and separate as butter.Answer: Churning/Centrifugation.
  26. f. Oil from water
  27. Identify the mixture.
    Oil and water are immiscible liquids.
  28. Observe the density difference.
    Oil forms the upper layer while water forms the lower layer.
  29. Select the separation method.
    Separating funnel is used.
  30. Perform the separation.
    Water is allowed to flow out first through the stopcock, leaving oil behind.
    Answer: Separating Funnel (Decantation).
  31. g. Tea leaves from tea
  32. Identify the mixture.
    Tea leaves are insoluble solids suspended in liquid tea.
  33. Observe the difference in particle size.
    Tea leaves are large enough to be retained by a filter.
  34. Select the separation method.
    Filtration is used.
  35. Perform the separation.
    Tea is poured through a strainer or filter which retains the leaves.
    Answer: Filtration.
  36. h. Iron pins from sand
  37. Identify the components.
    Iron pins and sand are mixed together.
  38. Observe the difference in magnetic property.
    Iron is magnetic while sand is non-magnetic.
  39. Select the separation method.
    Magnetic separation is used.
  40. Perform the separation.
    A magnet attracts iron pins, leaving sand behind.
    Answer: Magnetic Separation.
  41. i. Wheat grains from husk
  42. Identify the mixture.
    Wheat grains are mixed with husk.
  43. Observe the density difference.
    Husk is much lighter than wheat grains.
  44. Select the separation method.
    Winnowing is used.
  45. Perform the separation.
    Air current carries away the lighter husk while heavier wheat grains fall down.
    Answer: Winnowing.
  46. j. Fine mud particles suspended in water
  47. Identify the mixture.
    Fine mud particles are suspended in water.
  48. Observe the density difference.
    Mud particles are heavier than water.
  49. Select the separation method.
    Sedimentation followed by decantation or filtration can be used.
  50. Perform the separation.
    Mud particles settle at the bottom. The clear water is carefully poured off. Further purification can be done by filtration.
    Answer: Sedimentation and Decantation (or Filtration).
🎯 Exam Significance Exam Significance ›
  • Frequently asked in CBSE school examinations as direct short-answer questions.
  • Tests understanding of physical properties used in separation techniques.
  • Forms the conceptual foundation for laboratory experiments in Chemistry.
  • Important for NTSE, Olympiads, Navodaya, Sainik School, and other scholarship examinations.
  • Questions based on choosing the correct separation method are commonly asked in MCQs.
  • Develops analytical thinking by connecting physical properties with practical applications.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  10 points

  1. Every separation technique is based on one or more differences in physical properties.

  2. Evaporation and crystallization are used for separating dissolved solids from solutions.

  3. Sublimation separates substances that directly change from solid to vapour.

  4. Filtration separates insoluble solids from liquids.

  5. Magnetic separation works when one component is magnetic.

  6. Chromatography separates coloured components and dissolved substances.

  7. Separating funnel is used for immiscible liquids.

  8. Winnowing depends on differences in weight and density.

  9. Sedimentation and decantation are useful for heavier suspended impurities.

  10. Understanding the property difference is the key to selecting the correct separation method.
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Q2 →
Q2
NUMERIC3 marks
Write the steps you would use for making tea. Use the words solution, solvent, solute, dissolve, soluble, insoluble, filtrate and residue.
📘 Concept & Theory Concept Builder ›

Making tea is an excellent example of the formation of a solution and the separation of components using filtration. During tea preparation, some substances dissolve in water, while others remain undissolved. This process helps us understand important terms such as solvent, solute, soluble, insoluble, filtrate, and residue.

In a solution:

  • The substance present in larger quantity is called the solvent.
  • The substance that dissolves in the solvent is called the solute.
  • Substances that dissolve are called soluble.
  • Substances that do not dissolve are called insoluble.
  • The clear liquid obtained after filtration is called the filtrate.
  • The solid left behind on the filter is called the residue.
🗺️ Solution Roadmap Step-by-step Plan ›

  1. Identify the solvent and solutes used in making tea.

  2. Understand which substances dissolve and which do not.

  3. Observe the formation of a solution.

  4. Apply filtration to separate insoluble tea leaves.

  5. Identify the filtrate and residue.

📊 Graph / Figure Graph / Figure ›
THE SCIENTIFIC PROCESS OF MAKING TEA 1. Prepare the Solvent Boil water, which acts as the solvent. SOLVENT: The liquid in which substances dissolve. 2. Add the Solute Place tea leaves (the solute) into the water. SOLUTE: The solid being dissolved. 3. Dissolving Process The soluble parts of the leaves dissolve into the water. DISSOLVE & SOLUBLE: Soluble parts mix completely. 4. Filtration Pour through a strainer to separate insoluble leaves. INSOLUBLE: Parts that do not dissolve. Final Products The liquid tea is the filtrate and solution; the leaves are the residue.
THE SCIENTIFIC PROCESS OF MAKING TEA
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  9 steps
  1. Take water in a pan and heat it. Here, water acts as the solvent because it is the medium in which other substances dissolve.
  2. Add sugar to the hot water. Sugar is the solute. Sugar is soluble in water and therefore it dissolves completely.
  3. Add milk to the mixture and stir well.
  4. Add tea leaves and boil the mixture for a few minutes so that the flavour and colour of the tea leaves mix with the liquid.
  5. The sugar dissolved in water forms a solution. Thus, the tea being prepared contains dissolved substances mixed uniformly in the solvent.
  6. Tea leaves are insoluble in water because they do not dissolve in it even after boiling.
  7. Pour the prepared tea through a tea strainer. This process is called filtration.
  8. The liquid tea that passes through the strainer is called the filtrate.
  9. The tea leaves that remain on the strainer are called the residue.
💡 Answer Final Answer ›
Answer: Water acts as the solvent, sugar acts as the solute and dissolves in water because it is soluble. Tea leaves are insoluble and are separated by filtration. The liquid tea obtained is the filtrate, while the tea leaves left on the strainer are the residue.
🎯 Exam Significance Exam Significance ›
  • Frequently asked in CBSE examinations to test understanding of solutions and filtration.
  • Helps students apply scientific terms to a real-life activity.
  • Strengthens concepts related to homogeneous and heterogeneous mixtures.
  • Important for MCQs, short-answer questions, and competency-based questions.
  • Forms the foundation for understanding laboratory separation techniques.
  • Useful for NTSE, Olympiads, scholarship examinations, and other competitive entrance tests.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  8 points

  1. Water is the solvent in tea preparation.

  2. Sugar is the solute and dissolves because it is soluble in water.

  3. A solution is formed when a solute dissolves uniformly in a solvent.

  4. Tea leaves are insoluble in water.

  5. Filtration is used to separate insoluble solids from liquids.

  6. The liquid obtained after filtration is called the filtrate.

  7. The solid left behind after filtration is called the residue.

  8. Tea making is a practical example of solution formation and filtration.
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2 / 11  ·  18%
Q3 →
Q3
NUMERIC3 marks
Pragya tested the solubility of three different substances at different temperatures and collected the data as given below (results are given in the following table, as grams of substance dissolved in 100 grams of water to form a saturated solution).
Substance Dissolved Temperature in K
283 293 313 333 353
solubility
Potassium nitrate 21 33 62 106 167
Sodium chloride 36 36 36 37 37
Potassium chloride 35 35 40 46 54
Ammonium chloride 24 37 41 55 66
  1. What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 grams of water at 313 K?
  2. Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.
  3. Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature?
  4. What is the effect of change of temperature on the solubility of a salt?
📘 Concept & Theory Concept Builder ›

The amount of a solute that dissolves in a given quantity of solvent at a specified temperature is called its solubility. Solubility is usually expressed as the mass of solute dissolved in 100 g of water to form a saturated solution.

A saturated solution contains the maximum amount of solute that can dissolve at a given temperature. Any additional solute remains undissolved.

Temperature plays an important role in solubility. For most solid salts, solubility increases with an increase in temperature. Therefore, a hot saturated solution often deposits crystals when cooled.

🗺️ Solution Roadmap Step-by-step Plan ›

  1. Read the solubility value from the table at the specified temperature.

  2. Use the definition of solubility to calculate the required mass when necessary.

  3. Compare solubility values to identify the most soluble salt.

  4. Analyze how solubility changes with temperature.

  5. Apply the concept of crystallization wherever a hot saturated solution is cooled.

📊 Graph / Figure Graph / Figure ›
Effect of Temperature on Solubility020406080100120140160180280290300310320330340350360Temperature (K)Solubility (g/100g Water)KNO₃NH₄ClKClNaCl
Solubility v/s Temperature
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  20 steps
  1. (a) What mass of potassium nitrate would be needed to produce a saturated solution of potassium nitrate in 50 g of water at 313 K?
  2. Theory Used

    Solubility tells us the mass of solute that dissolves in 100 g of water. If the amount of water changes, we use the unitary method to calculate the required mass of solute.

  3. From the table:
  4. Solubility of potassium nitrate at 313 K\[= 62 \text{ g per } 100 \text{ g of water}\]
  5. Therefore,\[100 \text{ g water } \rightarrow 62 \text{ g KNO}_3\]
  6. \[\begin{aligned}50 \text{ g water } \rightarrow \frac{62 \times 50}{100}= 31 \text{ g}\end{aligned}\]
  7. (b) Pragya makes a saturated solution of potassium chloride in water at 353 K and leaves the solution to cool at room temperature. What would she observe as the solution cools? Explain.
  8. Theory Used

    The solubility of most salts decreases when temperature decreases. If a saturated solution prepared at a higher temperature is cooled, the excess dissolved solute separates out as crystals.

  9. From the table:
  10. Solubility of potassium chloride at 353 K\[= 54 \text{ g per } 100 \text{ g water}\]
  11. Solubility of potassium chloride at room temperature (approximately 293 K)\[= 35 \text{ g per } 100 \text{ g water}\]
  12. Thus, when the hot saturated solution cools, the amount of potassium chloride that can remain dissolved decreases.
  13. The excess potassium chloride comes out of the solution in the form of crystals.
  14. This process is known as crystallization.
  15. (c) Find the solubility of each salt at 293 K. Which salt has the highest solubility at this temperature?
  16. Theory Used

    To determine the solubility at a given temperature, we directly read the values from the table and compare them.

  17. From the given table, at 293 K:
  18. Salt Solubility at 293 K (g per 100 g water)
    Potassium nitrate (KNO₃) 33
    Sodium chloride (NaCl) 36
    Potassium chloride (KCl) 35
    Ammonium chloride (NH₄Cl) 37
  19. Comparing all values:\[37 > 36 > 35 > 33\]
  20. Therefore, ammonium chloride has the highest solubility at 293 K.
  21. (d) What is the effect of a change in temperature on the solubility of a salt?
  22. Theory Used

    Solubility is temperature dependent. Different salts show different changes in solubility with temperature, but most solid salts become more soluble as temperature increases.

    • Potassium nitrate shows a very large increase in solubility with temperature.
    • Potassium chloride and ammonium chloride also show an increase in solubility.
    • Sodium chloride shows only a very small increase in solubility.
    • Thus, the effect of temperature is not identical for all salts.
  24. From the data, it is evident that as temperature increases, the solubility of most salts increases.
🎯 Exam Significance Exam Significance ›
  • Tests interpretation of tabular data and scientific observations.
  • Frequently asked in CBSE competency-based and case-based questions.
  • Strengthens understanding of saturated solutions and solubility.
  • Introduces the concept of crystallization from hot saturated solutions.
  • Important for NTSE, Olympiads, scholarship tests, and foundation courses for JEE/NEET.
  • Develops graph-reading and data-analysis skills often tested in competitive examinations.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  8 points

  1. Solubility is the amount of solute dissolved in 100 g of water at a given temperature.

  2. A saturated solution contains the maximum amount of dissolved solute.

  3. Unitary method is used to calculate solubility for different quantities of water.

  4. Cooling a hot saturated solution may lead to crystallization.

  5. Potassium nitrate shows the greatest increase in solubility with temperature.

  6. Sodium chloride shows very little change in solubility with temperature.

  7. At 293 K, ammonium chloride is the most soluble among the given salts.

  8. Most solid salts become more soluble as temperature increases.
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3 / 11  ·  27%
Q4 →
Q4
NUMERIC3 marks
Explain the following giving examples.
(a) Saturated solution
(b) Pure substance
(c) Colloid
(d) Suspension
📘 Concept & Theory Concept Builder ›

Matter around us exists in different forms. Depending on the nature of particles and how they are mixed, matter can be classified into pure substances and mixtures. Mixtures may further exist as true solutions, colloids, or suspensions.

To understand these concepts clearly, it is important to compare the composition, particle size, uniformity, and physical properties of different types of matter.

🗺️ Solution Roadmap Step-by-step Plan ›

  1. Define the scientific term.

  2. Understand its important characteristics.

  3. Differentiate it from related concepts wherever necessary.

  4. Support the definition with suitable examples.

  5. Relate the concept to everyday life situations.

📊 Graph / Figure Graph / Figure ›
Classification of MatterMATTERPURE SUBSTANCEMIXTUREELEMENTCOMPOUNDHOMOGENEOUS(Solutions)HETEROGENEOUSCOLLOIDSUSPENSIONChemistry Classification Hierarchy
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  16 steps
  1. (a) Saturated Solution
  2. Theory

    A solution can dissolve only a limited amount of solute at a given temperature. Once this maximum limit is reached, no more solute can dissolve in the solvent.

  3. Explanation

    A saturated solution is a solution that contains the maximum amount of solute that can dissolve in a given amount of solvent at a particular temperature.

    If additional solute is added to a saturated solution, it remains undissolved and settles at the bottom.

  4. Example

    When sugar is continuously added to water, a stage comes when no more sugar dissolves. The resulting solution is called a saturated sugar solution.

  5. Answer: A saturated solution is a solution that has dissolved as much solute as it can at a given temperature. Example: Saturated solution of sugar in water.
  6. (b) Pure Substance
  7. Theory

    Pure substances consist of only one kind of particles and have a fixed composition throughout the sample. Their properties remain uniform at every point.

  8. Explanation

    A pure substance is a form of matter that contains only one type of particle and has a definite chemical composition.

    Pure substances may be elements or compounds.

    • Elements contain only one type of atom.
    • Compounds contain chemically combined elements in fixed proportions.
  9. Examples
    • Gold (Au)
    • Silver (Ag)
    • Distilled water (H₂O)
    • Carbon dioxide (CO₂)
  10. Answer: A pure substance contains only one type of particle and has a fixed composition. Examples: Gold, distilled water, and carbon dioxide.
  11. (c) Colloid
  12. Theory

    Colloids have particle sizes intermediate between those of true solutions and suspensions. Their particles are small enough to remain dispersed but large enough to scatter light.

  13. Explanation

    A colloid is a heterogeneous mixture in which very small particles of one substance are uniformly distributed throughout another substance.

    Although colloids appear homogeneous to the naked eye, they are actually heterogeneous mixtures.

    Colloidal particles do not settle down on standing and cannot be separated by ordinary filtration.

  14. Examples
    • Milk
    • Fog
    • Smoke
    • Butter
    • Jelly
  15. Answer: A colloid is a heterogeneous mixture in which very small particles are uniformly spread throughout the medium. Example: Milk.
  16. (d) Suspension
  17. Theory

    Suspensions contain comparatively larger particles that remain dispersed for some time but settle down on standing due to gravity.

  18. Explanation

    A suspension is a heterogeneous mixture in which insoluble solid particles remain suspended throughout the medium.

    The particles of a suspension are large enough to be seen with the naked eye.

    These particles settle down when left undisturbed and can be separated by filtration.

  19. Examples
    • Chalk powder in water
    • Muddy water
    • Sand in water
  20. Answer: A suspension is a heterogeneous mixture in which insoluble particles remain suspended throughout the medium. Example: Chalk powder in water.
🗓️ Quick Comparison Table Solution | Colloid | Suspension ›
Property Solution Colloid Suspension
Nature Homogeneous Heterogeneous Heterogeneous
Particle Visibility Not visible Not visible to naked eye Visible
Settling of Particles No No Yes
Filtration Not possible Not possible by ordinary filtration Possible
Example Salt solution Milk Muddy water
🎯 Exam Significance Exam Significance ›
  • Frequently asked as a definition-based question in CBSE board examinations.
  • Important for understanding the classification of matter.
  • Forms the basis for distinguishing between solutions, colloids, and suspensions.
  • Commonly appears in MCQs, assertion-reason questions, and competency-based questions.
  • Useful for NTSE, Olympiads, scholarship examinations, and foundation-level entrance tests.
  • Concepts learned here are used extensively in higher classes of Chemistry.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  9 points

  1. A saturated solution contains the maximum amount of dissolved solute at a given temperature.

  2. A pure substance contains only one type of particle and has a fixed composition.

  3. Colloids appear homogeneous but are actually heterogeneous mixtures.

  4. Colloidal particles do not settle down on standing.

  5. Suspensions contain large insoluble particles that settle on standing.

  6. Suspension particles can be separated by filtration.

  7. Milk is a common example of a colloid.

  8. Muddy water is a common example of a suspension.

  9. Understanding these concepts helps classify different forms of matter correctly.
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Q5
NUMERIC3 marks
Classify each of the following as a homogeneous or heterogeneous mixture.
soda water, wood, air, soil, vinegar, filtered tea.
📘 Concept & Theory Concept Builder ›

Mixtures are classified into two broad categories based on the uniformity of their composition: homogeneous mixtures and heterogeneous mixtures.

A homogeneous mixture has a uniform composition throughout. Its components are evenly distributed, and the different parts of the mixture cannot be distinguished with the naked eye.

A heterogeneous mixture has a non-uniform composition. Its components are not distributed uniformly and may be distinguished physically.

To classify a mixture correctly, we should observe whether its composition is uniform throughout the sample.

🗺️ Solution Roadmap Step-by-step Plan ›

  1. Understand the meaning of homogeneous and heterogeneous mixtures.

  2. Examine the composition of each substance.

  3. Check whether the components are uniformly distributed.

  4. Classify the substance accordingly.

  5. Support the classification with a scientific reason.

📊 Graph / Figure Graph / Figure ›
Homogeneous vs Heterogeneous Mixtures HOMOGENEOUS Uniform Composition One Phase (Solution) HETEROGENEOUS Non-uniform Composition Multiple Phases (Colloid/Suspension)
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  1 step
  1. Substance Classification Reason
    Soda Water Homogeneous Mixture Carbon dioxide gas is uniformly dissolved in water, forming a solution with uniform composition throughout.
    Wood Heterogeneous Mixture Wood contains different components such as cellulose, lignin, fibres, and moisture that are not uniformly distributed.
    Air Homogeneous Mixture Air is a uniform mixture of gases such as nitrogen, oxygen, carbon dioxide, and noble gases. Its composition is generally uniform throughout.
    Vinegar Homogeneous Mixture Vinegar is a solution of acetic acid in water. The acetic acid is uniformly distributed throughout the solution.
    Filtered Tea Homogeneous Mixture After filtration, tea leaves are removed and the remaining liquid has a uniform composition.
🗓️ Final Answer Homogeneous | Heterogeneous ›

Final Answer

Substance Type of Mixture
Soda Water Homogeneous
Wood Heterogeneous
Air Homogeneous
Vinegar Homogeneous
Filtered Tea Homogeneous

Important Correction: Air is a homogeneous mixture, not a heterogeneous mixture. The gases present in air are uniformly mixed under normal conditions.

🎯 Exam Significance Exam Significance ›
  • Frequently asked as a classification-based question in CBSE examinations.
  • Tests understanding of homogeneous and heterogeneous mixtures.
  • Important for competency-based and assertion-reason questions.
  • Forms the foundation for understanding solutions, colloids, and suspensions.
  • Useful for NTSE, Olympiads, scholarship tests, and foundation-level entrance examinations.
  • Helps students apply theoretical concepts to everyday substances.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  8 points

  1. Homogeneous mixtures have uniform composition throughout.

  2. Heterogeneous mixtures have non-uniform composition.

  3. Soda water is a homogeneous mixture because carbon dioxide is uniformly dissolved in water.

  4. Wood is a heterogeneous mixture because its components are not uniformly distributed.

  5. Air is generally considered a homogeneous mixture of gases.

  6. Vinegar is a homogeneous solution of acetic acid in water.

  7. Filtered tea is homogeneous because insoluble tea leaves have been removed.

  8. Correct classification depends on the uniformity of composition.
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5 / 11  ·  45%
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Q6
NUMERIC3 marks
How would you confirm that a colourless liquid given to you is pure water?
📘 Concept & Theory Concept Builder ›

A pure substance has fixed physical properties such as melting point, boiling point, density, and composition. These characteristic properties remain constant and can be used to identify a substance.

Pure water is a compound with the chemical formula H₂O. Unlike impure water, it has definite boiling and freezing points at normal atmospheric pressure.

Therefore, to confirm whether a colourless liquid is pure water, we compare its physical properties with the known properties of pure water.

🗺️ Solution Roadmap Step-by-step Plan ›

  1. Observe the physical appearance of the liquid.

  2. Measure its boiling point.

  3. Measure its freezing point.

  4. Check whether any residue remains after evaporation.

  5. Compare the observations with the standard properties of pure water.

📊 Graph / Figure Graph / Figure ›
Water Purity Confirmation Tests Illustration showing physical and chemical tests to confirm if a colorless liquid is pure water. How to Confirm Pure Water? Physical and Chemical Verification Methods Colorless Liquid 1. Boiling Point 100°C Pure water boils at exactly 100°C 2. Melting Point 0°C Pure water freezes at exactly 0°C Chemical Identification Anhydrous Copper(II) Sulfate turns WHITE to BLUE in presence of water. Note: Only physical tests confirm PURITY. Chemical tests only confirm IDENTITY.
Confirmation of Pure Water
📖 Theory Used ›

Pure substances possess fixed melting and boiling points. Pure water freezes at

\[ 273\ \text{K} \; (0^\circ\text{C}) \]

and boils at

\[ 373\ \text{K} \; (100^\circ\text{C}) \]

at normal atmospheric pressure.

If a liquid contains dissolved impurities, its boiling point and freezing point generally differ from these standard values.

✏️ Solution Complete Solution ›
Step-by-step Solution  ·  9 steps
  1. Take a sample of the given colourless liquid in a clean beaker or flask.
  2. Heat the liquid carefully and measure its boiling point using a thermometer.
  3. Observe the temperature at which the liquid starts boiling continuously.
  4. If the liquid boils at \[ 373\ \text{K} \] (or \[ 100^\circ\text{C} \] ) under normal atmospheric pressure, it shows one characteristic property of pure water.
  5. Cool another sample of the liquid and determine its freezing point.
  6. If it freezes at \[ 273\ \text{K} \] or \[ 0^\circ\text{C} \] , it shows another characteristic property of pure water.
  7. Evaporate a small quantity of the liquid in a clean evaporating dish.
  8. If no solid residue is left behind after complete evaporation, it further confirms the absence of dissolved impurities.
  9. Combining these observations provides strong evidence that the liquid is pure water.
✅ Final Answer ›

A colourless liquid can be confirmed as pure water by checking its characteristic physical properties. Pure water boils at

\[ 373\ \text{K} \; (100^\circ\text{C}) \]

and freezes at

\[ 273\ \text{K} \; (0^\circ\text{C}) \]

under normal atmospheric pressure. Also, pure water leaves no residue after complete evaporation. Therefore, if the given liquid shows these properties, it can be identified as pure water.

🎯 Exam Significance Exam Significance ›
  • Frequently asked as a concept-based short-answer question in CBSE examinations.
  • Tests understanding of characteristic properties of pure substances.
  • Highlights the importance of melting and boiling points in identifying substances.
  • Forms the basis for laboratory tests used in chemistry.
  • Important for NTSE, Olympiads, scholarship tests, and foundation-level competitive examinations.
  • Develops scientific reasoning and experimental observation skills.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  7 points

  1. Pure substances have fixed characteristic properties.

  2. Pure water freezes at 273 K (0°C).

  3. Pure water boils at 373 K (100°C).

  4. Impurities alter the boiling point and freezing point of water.

  5. Pure water leaves no residue after complete evaporation.

  6. Boiling point and freezing point are reliable methods for identifying pure substances.

  7. Physical properties are commonly used to test purity in chemistry.
← Q5
6 / 11  ·  55%
Q7 →
Q7
NUMERIC3 marks
Which of the following materials fall in the category of a “pure substance”?
  1. Ice
  2. Milk
  3. Iron
  4. Hydrochloric acid
  5. Calcium oxide
  6. Mercury
  7. Bricks
  8. Wood
  9. Air
📘 Concept & Theory Concept Builder ›

A pure substance consists of only one type of particle and has a fixed chemical composition throughout. Pure substances may be classified as:

  • Elements – made up of only one kind of atom.
  • Compounds – formed when two or more elements combine chemically in a fixed ratio.

Mixtures, on the other hand, contain two or more substances physically mixed in any proportion and do not have a fixed composition. Therefore, mixtures are not pure substances.

🗺️ Solution Roadmap Step-by-step Plan ›

  1. Identify whether the substance is an element, compound, or mixture.

  2. Check whether it has a fixed chemical composition.

  3. If it consists of only one type of particle, classify it as a pure substance.

  4. If it contains multiple substances physically mixed together, classify it as a mixture.

  5. Prepare the final list of pure substances.

📊 Graph / Figure Graph / Figure ›
Classification of Pure Substances Educational graphic showing which materials are pure substances vs mixtures. Identifying Pure Substances Elements and Compounds vs. Mixtures PURE SUBSTANCES (Elements & Compounds) Ice (Compound) Iron (Element) Calcium oxide (Compound) Mercury (Element) These have a fixed chemical composition. MIXTURES (Impure Substances) ò Milk ò Hydrochloric acid (Solution) ò Bricks ò Wood ò Air Composition varies by source/type. Answer: Ice, Iron, Calcium Oxide, and Mercury are Pure Substances.
📖 Theory Used ›
Pure substances have a fixed composition and consist of only one kind of particle. Elements and compounds are pure substances, whereas mixtures such as air, milk, and wood are not pure because their composition can vary.
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  1 step
  1. Material Type Reason
    Ice Pure Substance Ice is solid water consisting only of H₂O molecules. It has a fixed composition.
    Milk Not a Pure Substance Milk is a colloidal mixture containing water, fats, proteins, minerals, and other substances.
    Iron Pure Substance Iron is an element consisting of only one type of atom (Fe).
    Hydrochloric Acid Not a Pure Substance (as commonly used) Hydrochloric acid is usually an aqueous solution of hydrogen chloride (HCl) in water and is therefore a mixture. Only pure hydrogen chloride gas (HCl) is a pure substance.
    Calcium Oxide Pure Substance Calcium oxide (CaO) is a compound with a fixed chemical composition.
    Mercury Pure Substance Mercury is an element consisting only of mercury atoms (Hg).
    Brick Not a Pure Substance Brick contains clay, sand, lime, and several other components mixed together.
    Wood Not a Pure Substance Wood contains cellulose, lignin, resins, water, and many other substances.
    Air Not a Pure Substance Air is a homogeneous mixture of nitrogen, oxygen, carbon dioxide, water vapour, and noble gases.
✅ Final Answer ›

The following materials are classified as pure substances:

  • Ice (H₂O) – Compound
  • Iron (Fe) – Element
  • Calcium Oxide (CaO) – Compound
  • Mercury (Hg) – Element

Therefore,

Pure Substances: Ice, Iron, Calcium Oxide, and Mercury.

⚡ Exam Alert ›
Students often mark Hydrochloric Acid as a pure substance. In NCERT context, hydrochloric acid generally refers to HCl dissolved in water, which is a mixture. Therefore, it is not included among the pure substances.
🎯 Exam Significance Exam Significance ›
  • Frequently asked in CBSE board examinations as a classification-based question.
  • Tests understanding of elements, compounds, and mixtures.
  • Important for MCQs, assertion-reason questions, and competency-based questions.
  • Develops the ability to distinguish pure substances from mixtures.
  • Useful for NTSE, Olympiads, scholarship examinations, and foundation-level entrance tests.
  • Forms the basis for higher-level chemistry concepts.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  8 points

  1. Pure substances have a fixed chemical composition.

  2. Elements and compounds are pure substances.

  3. Ice is pure water in solid form and is therefore a pure substance.

  4. Iron and mercury are pure substances because they are elements.

  5. Calcium oxide is a pure substance because it is a compound.

  6. Milk, air, wood, and brick are mixtures and hence not pure substances.<

  7. Hydrochloric acid is generally a solution of HCl in water and is therefore a mixture.

  8. Correct identification of pure substances depends on fixed composition and uniform properties.
← Q6
7 / 11  ·  64%
Q8 →
Q8
NUMERIC3 marks
Identify the solutions among the following mixtures.
  1. Soil
  2. Sea water
  3. Air
  4. Coal
  5. Soda water
📘 Concept & Theory Concept Builder ›

A solution is a homogeneous mixture of two or more substances. The composition of a solution is uniform throughout, and its components cannot be distinguished by the naked eye.

Solutions may exist in different states:

  • Solid in liquid (salt in water)
  • Gas in liquid (carbon dioxide in water)
  • Gas in gas (air)

To identify whether a mixture is a solution, we need to check whether its composition is uniform throughout and whether it forms a single phase.

🗺️ Solution Roadmap Step-by-step Plan ›

  1. Examine the composition of each mixture.

  2. Determine whether the mixture is homogeneous or heterogeneous.

  3. Identify mixtures having uniform composition throughout.

  4. Classify homogeneous mixtures as solutions.

  5. Prepare the final list of solutions.

📊 Graph / Figure Graph / Figure ›
Identifying Solutions Solutions Sea Water Air Soda Water Not Solutions Soil Coal Heterogeneous Mixtures
📖 Theory Used ›
A solution is always a homogeneous mixture. Therefore, if the components are uniformly distributed and cannot be distinguished separately, the mixture is classified as a solution.
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  1 step
  1. Mixture Solution or Not? Reason
    Soil Not a Solution Soil contains sand, clay, minerals, humus, pebbles, and organic matter. Its composition is non-uniform, making it a heterogeneous mixture.
    Sea Water Solution Sea water consists mainly of salts dissolved uniformly in water. Therefore, it is a homogeneous mixture and hence a solution.
    Air Solution Air is a homogeneous mixture of gases such as nitrogen, oxygen, carbon dioxide, and noble gases. It is a gas-in-gas solution.
    Coal Not a Solution Coal contains carbon along with various hydrocarbons, mineral matter, and impurities. Its composition is not uniform.
    Soda Water Solution Soda water contains carbon dioxide gas dissolved uniformly in water under pressure, forming a homogeneous solution.
📖 Final Answer ›

The mixtures that are solutions are:

  • Sea Water
  • Air
  • Soda Water

The mixtures that are not solutions are:

  • Soil
  • Coal
🌟 Important Examination Point ›

Students often think that a solution can exist only in liquid form. This is incorrect. Air is also a solution because it is a homogeneous mixture of gases.

Similarly, soda water is an example of a gas dissolved in a liquid, while sea water is an example of a solid dissolved in a liquid.

🎯 Exam Significance Exam Significance ›
  • Frequently asked in CBSE board examinations as a classification-based question.
  • Tests understanding of the definition and characteristics of solutions.
  • Important for distinguishing homogeneous and heterogeneous mixtures.
  • Commonly appears in MCQs and competency-based questions.
  • Useful for NTSE, Olympiads, scholarship examinations, and foundation-level entrance tests.
  • Develops conceptual understanding of different types of solutions.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  8 points

  1. A solution is a homogeneous mixture.

  2. Sea water is a solution because salts are dissolved uniformly in water.

  3. Air is a gas-in-gas solution.

  4. Soda water is a gas-in-liquid solution.

  5. Soil is a heterogeneous mixture and not a solution.

  6. Coal is not a solution because its composition is not uniform.

  7. Solutions may exist in solid-liquid, gas-liquid, and gas-gas forms.

  8. Uniform composition is the key characteristic of a solution.
← Q7
8 / 11  ·  73%
Q9 →
Q9
NUMERIC3 marks
Which of the following will show “Tyndall effect”?
  1. Salt solution
  2. Milk
  3. Copper sulphate solution
  4. Starch solution
📘 Concept & Theory Concept Builder ›

The Tyndall Effect is the scattering of light by colloidal particles. When a beam of light passes through a colloid, the path of light becomes visible because the colloidal particles scatter the light in different directions.

True solutions do not show the Tyndall effect because their particles are extremely small and cannot scatter light. Colloids, however, have particle sizes large enough to scatter light and therefore exhibit the Tyndall effect.

Thus, to determine whether a mixture shows the Tyndall effect, we first identify whether it is a true solution or a colloid.

🗺️ Solution Roadmap Step-by-step Plan ›

  1. Understand the meaning of the Tyndall effect.

  2. Identify whether the given substance is a true solution or a colloid.

  3. Recall that true solutions do not scatter light.

  4. Recall that colloidal particles scatter light.

  5. Select the substances that are colloids.

📊 Graph / Figure Graph / Figure ›
Tyndall Effect Demonstration True Solution (Light beam invisible) Colloid (Light scattering visible)
Tyndall effect
📖 Theory ›
Colloidal particles have sizes large enough to scatter light. Therefore, colloids show the Tyndall effect. True solutions contain particles of molecular or ionic size that are too small to scatter light and hence do not show the Tyndall effect.
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  1 step
  1. Substance Type of Mixture Tyndall Effect Reason
    Salt Solution True Solution No Salt particles dissolve completely into ions and become too small to scatter light.
    Milk Colloid Yes Milk contains colloidal particles of fats and proteins that scatter light.
    Copper Sulphate Solution True Solution No Copper sulphate dissolves completely in water forming a homogeneous solution whose particles are too small to scatter light.
    Starch Solution Colloid Yes Starch forms a colloidal dispersion in water and its particles scatter light.
✅ Answer ›

The substances that will show the Tyndall Effect are:

  • Milk
  • Starch Solution

The substances that will not show the Tyndall Effect are:

  • Salt Solution
  • Copper Sulphate Solution
🎯 Exam Significance Exam Significance ›
  • Frequently asked in CBSE board examinations and MCQs.
  • Tests understanding of colloids and true solutions.
  • Directly linked to the chapter topic "Is Matter Around Us Pure?".
  • Important for assertion-reason and competency-based questions.
  • Useful for NTSE, Olympiads, scholarship examinations, and foundation-level entrance tests.
  • Helps distinguish between solutions, colloids, and suspensions using particle size.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  8 points

  1. The Tyndall effect is the scattering of light by colloidal particles.

  2. True solutions do not show the Tyndall effect.

  3. Colloids show the Tyndall effect because their particles are large enough to scatter light.

  4. Milk is a colloid and shows the Tyndall effect.

  5. Starch solution is a colloid and shows the Tyndall effect.

  6. Salt solution does not show the Tyndall effect.

  7. Copper sulphate solution does not show the Tyndall effect.

  8. The visibility of a light beam in fog, smoke, or milk is due to the Tyndall effect.
← Q8
9 / 11  ·  82%
Q10 →
Q10
NUMERIC2 marks
Classify the following into elements, compounds and mixtures.
  1. Sodium
  2. Soil
  3. Sugar solution
  4. Silver
  5. Calcium carbonate
  6. Tin
  7. Silicon
  8. Coal
  9. Air
  10. Soap
  11. Methane
  12. Carbon dioxide
  13. Blood
📘 Concept & Theory Concept Builder ›

Matter can be broadly classified into pure substances and mixtures.

Pure substances are further divided into:

  • Elements – Substances made up of only one type of atom and cannot be broken down into simpler substances by chemical methods.
  • Compounds – Substances formed when two or more elements combine chemically in a fixed ratio.

Mixtures contain two or more substances physically mixed together in any proportion. Their composition is variable, and the components retain their individual properties.

🗺️ Solution Roadmap Step-by-step Plan ›

  1. Identify whether the substance consists of one kind of atom.

  2. If yes, classify it as an element.

  3. f it contains chemically combined elements in a fixed ratio, classify it as a compound.

  4. If it contains two or more substances physically mixed, classify it as a mixture.

  5. Prepare the final classification table.

📊 Graph / Figure Graph / Figure ›
Classification of Matter Elements Sodium Silver Tin Silicon Compounds Calcium Carbonate Methane Carbon Dioxide Mixtures Soil Sugar Solution Coal Air Soap Blood
📖 Theory ›
Elements contain only one kind of atom. Compounds contain two or more elements chemically combined in a fixed proportion. Mixtures contain two or more substances physically mixed in variable proportions.
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  1 step
  1. Substance Classification Reason
    Sodium (Na) Element Consists of only one type of sodium atom.
    Soil Mixture Contains sand, clay, minerals, humus, and organic matter.
    Sugar Solution Mixture Consists of sugar dissolved in water, forming a homogeneous mixture.
    Silver (Ag) Element Contains only silver atoms.
    Calcium Carbonate (CaCO₃) Compound Contains calcium, carbon, and oxygen chemically combined in a fixed ratio.
    Tin (Sn) Element Contains only tin atoms.
    Silicon (Si) Element Contains only silicon atoms.
    Coal Mixture Contains carbon, hydrocarbons, mineral matter, and other impurities.
    Air Mixture Contains nitrogen, oxygen, carbon dioxide, water vapour, and noble gases.
    Soap Mixture Contains sodium salts of fatty acids along with perfumes, colours, and additives.
    Methane (CH₄) Compound Contains carbon and hydrogen chemically combined in a fixed ratio.
    Carbon Dioxide (CO₂) Compound Contains carbon and oxygen chemically combined in a fixed ratio.
    Blood Mixture Contains plasma, red blood cells, white blood cells, platelets, proteins, and dissolved salts.
✅ Answer ›
Elements Compounds Mixtures
Sodium
Silver
Tin
Silicon 		Calcium Carbonate (CaCO₃)
Methane (CH₄)
Carbon Dioxide (CO₂) 		Soil
Sugar Solution
Coal
Air
Soap
Blood
🧠 Memory Tip ›

If a substance has a definite chemical formula such as \[ CaCO_3,\ CH_4,\ CO_2 \] it is usually a compound.

If it is represented by a single chemical symbol such as \[ Na,\ Ag,\ Sn,\ Si \] it is an element.

If it consists of several substances physically mixed together, it is a mixture.

🎯 Exam Significance Exam Significance ›
  • One of the most frequently asked classification questions from this chapter.
  • Tests understanding of elements, compounds, and mixtures.
  • Important for MCQs, match-the-following, and competency-based questions.
  • Forms the conceptual foundation for chemistry in higher classes.
  • Useful for NTSE, Olympiads, scholarship tests, and foundation courses for JEE/NEET.
  • Helps students identify substances based on their composition.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  8 points

  1. Elements contain only one type of atom.

  2. Compounds contain chemically combined elements in a fixed ratio.

  3. Mixtures contain physically combined substances in variable proportions.

  4. Sodium, Silver, Tin, and Silicon are elements.

  5. Calcium Carbonate, Methane, and Carbon Dioxide are compounds.

  6. Soil, Air, Coal, Soap, Blood, and Sugar Solution are mixtures.

  7. Compounds have fixed chemical formulas.

  8. Mixtures can often be separated by physical methods.
← Q9
10 / 11  ·  91%
Q11 →
Q11
NUMERIC3 marks
Which of the following are chemical changes?
  1. Growth of a plant
  2. Rusting of iron
  3. Mixing of iron filings and sand
  4. Cooking of food
  5. Digestion of food
  6. Freezing of water
  7. Burning of a candle
📘 Concept & Theory Concept Builder ›

Changes occurring in matter can be classified as physical changes and chemical changes.

In a physical change, only the physical properties such as shape, size, or state of a substance change. No new substance is formed.

In a chemical change, one or more new substances are formed with different properties. Such changes are usually irreversible and involve a change in chemical composition.

Common indicators of a chemical change include:

  • Formation of a new substance
  • Evolution of gas
  • Change in colour
  • Production or absorption of heat
  • Irreversibility of the process
🗺️ Solution Roadmap Step-by-step Plan ›

  1. Examine each process carefully.

  2. Check whether a new substance is formed.

  3. Determine whether the change is reversible or irreversible.

  4. Classify the process as physical or chemical.

  5. Identify all the chemical changes.

📊 Graph / Figure Graph / Figure ›
Physical Changes vs Chemical Changes Physical Changes No New Substance State Change Usually Reversible Chemical Changes New Substance Formed Change in Composition Usually Irreversible
📖 Theory Used ›
A process is considered a chemical change if it results in the formation of one or more new substances having properties different from those of the original substances.
✏️ Solution Complete Solution ›
Step-by-step Solution  ·  2 steps
  1. Process Type of Change Reason
    Growth of a Plant Chemical Change New substances such as carbohydrates, proteins, and plant tissues are formed through photosynthesis and other biochemical reactions.
    Rusting of Iron Chemical Change Iron reacts with oxygen and moisture to form a new substance, hydrated iron oxide (rust).
    Mixing of Iron Filings and Sand Physical Change No new substance is formed. The components retain their properties and can be separated using a magnet.
    Cooking of Food Chemical Change Heating causes chemical reactions that produce new substances with different taste, colour, texture, and aroma.
    Digestion of Food Chemical Change Complex food molecules are chemically broken down into simpler substances by enzymes.
    Freezing of Water Physical Change Only the state changes from liquid to solid. No new substance is formed.
    Burning of a Candle Both Physical and Chemical Change Melting of wax is a physical change, whereas burning of wax produces new substances such as carbon dioxide and water vapour, making it a chemical change.
  2. Detailed Explanation of Candle Burning

  3. Burning of a candle is an important example because it involves both physical and chemical changes.

    1. Wax near the flame melts. This is a physical change because only the state changes from solid wax to liquid wax.
    2. The molten wax vaporizes and burns in air. This is a chemical change because new substances are produced.
    3. During combustion:

    \[ \text{Wax} + \text{Oxygen} \rightarrow \text{Carbon Dioxide} + \text{Water Vapour} + \text{Heat} + \text{Light} \]

    Therefore, candle burning is considered both a physical and a chemical change.

✅ Final Answer ›

The following are chemical changes:

  • Growth of a plant
  • Rusting of iron
  • Cooking of food
  • Digestion of food
  • Burning of a candle (burning part)

The following are physical changes:

  • Mixing of iron filings and sand
  • Freezing of water
  • Melting of candle wax
⚡ Quick Revision ›
Chemical Changes Physical Changes
Growth of Plant Mixing Iron Filings and Sand
Rusting of Iron Freezing of Water
Cooking of Food Melting of Wax
Digestion of Food -
Burning of Wax -
🎯 Exam Significance Exam Significance ›
  • One of the most important conceptual questions from this chapter.
  • Frequently appears in CBSE board examinations and MCQs.
  • Tests the ability to distinguish physical and chemical changes.
  • Important for assertion-reason and competency-based questions.
  • Useful for NTSE, Olympiads, scholarship examinations, and foundation courses for JEE/NEET.
  • Forms the basis for understanding chemical reactions in higher classes.
🔑 Key Takeaways Key Takeaways ›
Key Takeaways  ·  8 points

  1. Chemical changes result in the formation of new substances.

  2. Physical changes do not produce new substances.

  3. Rusting of iron is a classic example of a chemical change.

  4. Cooking and digestion involve irreversible chemical reactions.

  5. Freezing of water is a physical change because only the state changes.

  6. Iron filings and sand can be separated physically; hence no chemical change occurs.

  7. Burning of a candle involves both physical and chemical changes.

  8. Formation of a new substance is the most important indicator of a chemical change.
← Q10
11 / 11  ·  100%
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Is Matter Around Us Pure | Science Class 9 | Academia Aeternum — Complete Notes & Solutions · academia-aeternum.com
Textbook Exercise – Is Matter Around Us Pure? The textbook exercises for this chapter are designed to help you apply what you have learned about pure substances, mixtures, solutions, colloids, and suspensions. Through these questions, you will practice identifying homogeneous and heterogeneous mixtures, understand the Tyndall effect, and recall important separation techniques such as filtration, evaporation, crystallization, distillation, and chromatography. By solving these exercises,…
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    Is Matter Around us Pure — Learning Resources

    📄 Detailed Notes
    🧠 Practice MCQs
    ✔️ True / False

    Frequently Asked Questions

    Distillation separates two miscible liquids based on their boiling points.

    It separates a mixture of two or more liquids with close boiling points.

    Sublimation separates solids that directly change into vapour on heating, such as camphor.

    Crystallization purifies solids by forming pure crystals from their saturated solutions.

    Chromatography separates colored mixtures based on solubility differences in a solvent.

    It is used to separate pigments from plant extracts or ink.

    Centrifugation separates heavier and lighter components by spinning rapidly.

    Decantation is the process of separating liquids from solids by pouring out the clear liquid.

    Sedimentation allows heavier particles to settle at the bottom due to gravity.

    Mixtures can be separated physically, while compounds require chemical methods to separate.

    Elements consist of one type of atom; compounds are formed by chemical bond between elements.

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