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CBSE Class 9 Chemistry Chapter 2 Is Matter Around Us Pure Worksheet with Answers

Chapter 2 of NCERT Class 9 Chemistry — Is Matter Around Us Pure — asks a simple question: is the water you drink, the air you breathe, or the salt in your kitchen genuinely pure, or are they mixtures? This worksheet translates NCERT theory into practice. You will tackle 40+ questions across MCQs, blanks, true/false, short answers, long answers, and a case study. Set aside 60 minutes, work through each section methodically, and then check the detailed answer key at the end to self-assess your grasp of pure substances, mixtures, solutions, colloids, and separation methods.

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Key takeaways

  • ✓Understand the difference between pure substances and mixtures, and identify homogeneous versus heterogeneous mixtures with real examples.
  • ✓Master separation techniques such as filtration, evaporation, distillation, chromatography, and centrifugation for different types of mixtures.
  • ✓Learn to distinguish solutions, suspensions, and colloids using properties like Tyndall effect, particle size, and settling behaviour.
  • ✓Recognize physical changes (reversible, no new substance) versus chemical changes (irreversible, new substance formed) in everyday scenarios.
  • ✓Practice NCERT-aligned MCQs, short-answer, and HOTS questions to build exam-ready confidence for CBSE Class 9 Chemistry Chapter 2.
  • ✓Complete answer key with explanations helps reinforce learning and clarifies common misconceptions in Is Matter Around Us Pure.

Quick Chapter Recap

Matter exists as either a pure substance (fixed composition, constant properties) or a mixture (two or more substances physically combined, variable composition). Mixtures are classified as homogeneous (uniform throughout, like salt water) or heterogeneous (visibly distinct components, like sand and iron filings). A solution is a special homogeneous mixture where solute dissolves completely in solvent. Colloids have intermediate particle size (1–1000 nm) and show the Tyndall effect; suspensions have larger particles that settle. Separation techniques depend on mixture type: filtration for insoluble solids, evaporation for dissolved solids, distillation for liquids with different boiling points, chromatography for coloured components, and centrifugation for dense particles. Physical changes (melting, dissolving) are reversible and form no new substance; chemical changes (burning, rusting) are usually irreversible and produce new substances with new properties. Mastering these distinctions is critical because every chemical reaction you study later begins with knowing what you are working with — pure or mixed, soluble or not, chemically changed or just physically altered.
  • Pure substance: one type of particle, fixed composition (e.g., distilled water, pure copper).
  • Mixture: two or more substances, no chemical bonding, variable composition (e.g., soil, air, saltwater).
  • Homogeneous mixture: uniform appearance (solutions, alloys). Heterogeneous: visibly distinct parts (sand + water).
  • Solute dissolves in solvent to form a solution; colloids scatter light (Tyndall effect); suspensions settle on standing.
  • Separation techniques: filtration, evaporation, distillation, chromatography, centrifugation — each suited to specific mixture types.

Section A — Multiple Choice Questions (MCQs)

This section tests your ability to quickly identify concepts, definitions, and real-world applications of Chapter 2. Each MCQ has four options; choose the single best answer. These questions mirror the style seen in CBSE term exams and school assessments. Work through all six questions without referring to notes first, then check your answers in the Answer Key section. Each correct answer carries 1 mark. Aim to finish this section in 10 minutes to build speed and accuracy. Pay special attention to questions on separation techniques and the Tyndall effect, as these are frequent exam favourites in NCERT Class 9 Chemistry Chapter 2.
  • Q1. Which of the following is a pure substance? (a) Air (b) Distilled water (c) Milk (d) Soil
  • Q2. A mixture of sand and water can be separated by: (a) Evaporation (b) Filtration (c) Distillation (d) Chromatography
  • Q3. The Tyndall effect is observed in: (a) Salt solution (b) Sugar solution (c) Milk (d) Pure water
  • Q4. Which of the following is a homogeneous mixture? (a) Sand and salt (b) Oil and water (c) Sugar dissolved in water (d) Smoke
  • Q5. When sugar dissolves in water, the change is: (a) Chemical change (b) Physical change (c) Both (d) Neither
  • Q6. Rusting of iron is an example of: (a) Physical change (b) Chemical change (c) Reversible change (d) No change

Section B — Fill in the Blanks

Complete each sentence with the correct term from Chapter 2. This section reinforces precise NCERT terminology and definitions. Read each statement carefully; often a single keyword distinguishes the right answer from a plausible wrong one. For example, 'colloid' versus 'suspension' or 'solute' versus 'solvent'. Use the exact words from your NCERT textbook where possible. Each blank carries 1 mark. Suggested time: 8 minutes for five questions. If you are unsure, move on and return after completing other sections — sometimes a later question will jog your memory. The Answer Key provides the correct term plus a one-line explanation to deepen understanding.
  • Q7. A __________ is a homogeneous mixture of two or more substances.
  • Q8. The substance present in larger amount in a solution is called the __________.
  • Q9. Particles in a __________ are large enough to scatter light but do not settle quickly.
  • Q10. The process of separating a liquid from a solution by heating is called __________.
  • Q11. A mixture in which different components are clearly visible is called a __________ mixture.

Section C — True or False

Evaluate each statement and mark it True or False. If a statement is false, mentally (or on paper) rewrite it to make it true — this deepens your grasp of the concept. This exercise sharpens your ability to spot subtle errors in wording, a skill tested in CBSE objective exams. Each statement is worth 1 mark. Allocate roughly 6 minutes for six statements. Watch out for absolutes like 'always', 'never', 'all' — they are often red flags. For instance, saying 'all mixtures are homogeneous' is false because heterogeneous mixtures exist. The Answer Key explains why each statement is true or false, helping you avoid similar mistakes in exams.
  • Q12. All solutions are homogeneous mixtures.
  • Q13. A suspension is a type of colloid.
  • Q14. Distilled water is a mixture.
  • Q15. The Tyndall effect is shown by true solutions.
  • Q16. Evaporation can separate a solute from a solvent.
  • Q17. Burning of paper is a physical change.

Section D — Short Answer Questions (2–3 marks each)

Answer each question in 30–50 words. These questions test your ability to explain concepts clearly and concisely, exactly as required in CBSE Class 9 Chemistry term exams. Focus on definitions, examples, and reasons. Use bullet points if it helps structure your answer. Each question carries 2 or 3 marks as indicated. Suggested time: 15 minutes for five questions. A good strategy: state the definition or main point in the first sentence, then give an example or reason in the next sentence. Avoid long introductions; jump straight to the science. The Answer Key provides model answers aligned to CBSE marking schemes, so compare your response and note any missing keywords or examples.
  • Q18. Define a pure substance. Give two examples. (2 marks)
  • Q19. Differentiate between homogeneous and heterogeneous mixtures with one example each. (3 marks)
  • Q20. What is the Tyndall effect? Name one mixture that shows it. (2 marks)
  • Q21. Explain why a solution of sugar in water is considered a physical change. (2 marks)
  • Q22. List two differences between a colloid and a suspension. (3 marks)

Section E — Long Answer and HOTS Questions (5 marks each)

These questions demand deeper understanding, application, and sometimes multi-step reasoning. Aim to write 80–120 words per answer, covering definitions, explanations, examples, and any diagrams if asked. HOTS (Higher Order Thinking Skills) questions may ask you to compare, analyse, or design an experiment. Allocate roughly 12 minutes per question (total 15 minutes for this section if doing all three). Structure your answer: introduce the concept, explain the science, give examples, and conclude with the significance. Use subheadings or numbered points for clarity. The Answer Key provides comprehensive model answers that mirror CBSE topper scripts, helping you understand what examiners look for in a 5-mark response.
  • Q23. Describe the process of separating a mixture of sand, salt, and water into its individual components. Mention each technique and the principle behind it. (5 marks)
  • Q24. Distinguish between physical and chemical changes. Give three points of difference and one example of each. (5 marks)
  • Q25. Explain what a solution is. Discuss solute, solvent, and give one example each of a solid-in-liquid, liquid-in-liquid, and gas-in-liquid solution. (5 marks)

Case Study Question

Read the short passage below carefully and answer the sub-questions that follow. Case-study questions are now a regular feature in CBSE exams, testing your ability to apply Chapter 2 concepts to real-world scenarios. This format mirrors the competency-based questions introduced in recent CBSE papers. Each sub-question typically carries 1 or 2 marks. Total for the case study: 4 marks. Suggested time: 8 minutes. Underline key facts in the passage — they often contain clues to the answers. Do not assume information not given; stick to what the passage states. The Answer Key explains each sub-question with reference to both the passage and NCERT theory, so you learn to bridge textbook knowledge and practical situations.

Complete Answer Key with Explanations

Below are the correct answers and brief explanations for every question in this worksheet. Use this key for self-assessment, not as a shortcut before attempting the questions. Compare your answers, award yourself marks honestly, and note recurring mistakes — they reveal which topics need revision. For MCQs and fill-in-the-blanks, the explanation clarifies why the answer is correct and why distractors are wrong. For short and long answers, model responses show how to structure your answer to earn full marks. For the case study, each sub-question is addressed with reference to both the passage and NCERT concepts. If you score below 70 percent, revisit the relevant NCERT sections and attempt the worksheet again after a few days. Consistent practice with worksheets like this one is the proven path to scoring 90+ in CBSE Class 9 Chemistry term exams.
  • A1. (b) Distilled water — pure substance with fixed composition H₂O. Air is a mixture of gases; milk is a colloid; soil is heterogeneous.
  • A2. (b) Filtration — sand is insoluble, so filter paper retains it while water passes through as filtrate.
  • A3. (c) Milk — a colloid scatters light (Tyndall effect). Salt/sugar solutions and pure water do not scatter light visibly.
  • A4. (c) Sugar dissolved in water — uniform throughout. Sand+salt, oil+water, and smoke are heterogeneous or appear non-uniform.
  • A5. (b) Physical change — sugar molecules disperse in water but remain sugar; no new substance forms, and the process is reversible by evaporation.
  • A6. (b) Chemical change — iron reacts with oxygen and moisture to form iron oxide (rust), a new substance with different properties; irreversible under normal conditions.
  • A7. solution
  • A8. solvent
  • A9. colloid
  • A10. evaporation
  • A11. heterogeneous
  • A12. True — solutions are by definition homogeneous mixtures.
  • A13. False — a suspension has larger particles that settle; a colloid has smaller particles (1–1000 nm) that do not settle easily.
  • A14. False — distilled water is a pure substance (only H₂O molecules).
  • A15. False — true solutions do not scatter light; only colloids and suspensions show the Tyndall effect.
  • A16. True — heating the solution evaporates the solvent (e.g., water), leaving the solute (e.g., salt) behind.
  • A17. False — burning paper is a chemical change; new substances (ash, smoke, CO₂) form and the change is irreversible.
  • A18. A pure substance has a fixed composition and constant properties. Examples: distilled water, pure copper. (2 marks)
  • A19. Homogeneous mixture: uniform composition throughout (e.g., saltwater). Heterogeneous mixture: visibly distinct components (e.g., sand in water). (3 marks: 1 for each definition + 1 for examples)
  • A20. The Tyndall effect is the scattering of light by colloidal particles, making the light beam visible. Example: milk. (2 marks)
  • A21. Dissolving sugar in water is a physical change because sugar molecules disperse uniformly without forming a new substance; the process is reversible by evaporation. (2 marks)
  • A22. (i) Colloids have particle size 1–1000 nm; suspensions have larger particles. (ii) Colloid particles do not settle easily; suspension particles settle on standing. (3 marks: 1.5 per difference)
  • A23. Step 1: Filtration — pour the mixture through filter paper; sand (insoluble) is retained, saltwater passes as filtrate. Step 2: Evaporation — heat the filtrate in an evaporating dish; water evaporates, salt crystals remain. Principle: Filtration separates insoluble solids from liquids; evaporation separates dissolved solids by removing the solvent as vapour. (5 marks: 2 for steps, 2 for principles, 1 for clarity)
  • A24. Physical change: no new substance, reversible, only physical properties change (e.g., ice melting). Chemical change: new substance forms, usually irreversible, chemical properties change (e.g., wood burning). Three differences: (i) substance identity, (ii) reversibility, (iii) energy change (chemical changes often release/absorb significant energy). (5 marks: 1 per difference + 1 per example)
  • A25. A solution is a homogeneous mixture where solute is completely dissolved in solvent. Solute: substance dissolved (smaller amount). Solvent: substance that dissolves solute (larger amount). Examples: solid-in-liquid (sugar in water), liquid-in-liquid (alcohol in water), gas-in-liquid (CO₂ in soda). (5 marks: 1 definition, 1 solute/solvent, 3 examples)
  • A26. Case Study Answers: (a) Heterogeneous mixture (tea leaves visible before straining). (b) Filtration (using sieve/strainer). (c) Tyndall effect; colloidal particles in tea scatter light. (d) Colloid; light beam visible indicates particle size between solution and suspension, characteristic of colloids. (4 marks total: 1 per sub-question)

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Tips to Maximise Your Worksheet Practice

Print this worksheet and attempt it in one sitting under exam conditions: no phone, no textbook, 60 minutes on the clock. This simulates real exam pressure and reveals time-management gaps. After finishing, use a different coloured pen to mark your answers against the Answer Key; this makes mistakes stand out when you review later. For every wrong answer, write a one-sentence correction in your notebook — active rewriting cements memory better than passive reading. If you scored below 70 percent, do not just reattempt immediately; first revise the relevant NCERT sections (pages 15–35 of the Class 9 Chemistry textbook), watch a concept video if available, then try again after two days. Track your scores across multiple attempts — improvement over time is a better confidence booster than a single perfect score. Finally, form a study group with two or three classmates: each person creates five original questions on Chapter 2, you swap and solve, then discuss answers together. Peer explanation often clarifies doubts faster than solo study because you hear the concept in a friend's words, which can click when textbook language does not.
  • Simulate exam conditions: 60 minutes, no notes, quiet space, then self-assess honestly.
  • Use two-colour marking: your answers in blue/black, corrections in red, so errors are visually obvious.
  • For every mistake, write a one-sentence reason why the correct answer is right; this active step prevents repeat errors.
  • Reattempt only after targeted revision of weak topics; mindless repetition without learning is wasted effort.
  • Form a study group; create and swap questions; teach each other — teaching forces you to understand deeply.

Common Mistakes Students Make in Chapter 2

Many students confuse 'homogeneous' with 'pure' — remember, a solution is homogeneous but not pure because it contains solute and solvent. Another frequent error: writing that suspensions are colloids. They are not; suspensions have much larger particles that settle, while colloid particles remain dispersed. In separation techniques, students often suggest evaporation for separating sand from water — wrong; filtration is needed because sand is insoluble. When asked about physical versus chemical change, watch out for tricky examples like dissolving salt (physical, reversible) versus dissolving an antacid tablet that fizzes (chemical, CO₂ gas forms). In MCQs, read all four options before choosing; often two options look similar but one uses 'mixture' and the other 'pure substance', and that single word makes all the difference. Finally, in case-study questions, students sometimes add information not present in the passage — stick strictly to what is given and apply Chapter 2 concepts only to those stated facts. Avoiding these pitfalls can easily swing your score from 60 percent to 85 percent in the same amount of study time.
  • Do not equate homogeneous with pure; saltwater is homogeneous but a mixture, not a pure substance.
  • Suspensions ≠ colloids; suspension particles are larger and settle, colloid particles stay dispersed and scatter light.
  • Use the right separation technique: filtration for insoluble solids, evaporation for dissolved solids, distillation for liquids.
  • Physical change example: ice melting (reversible, same substance). Chemical change: candle burning (new substances form).
  • In case studies, answer only what the passage supports; do not invent extra facts or assumptions.

Frequently asked questions

What is the difference between a pure substance and a mixture in Chapter 2?+
A pure substance has a fixed composition and uniform properties throughout (e.g., distilled water is always H₂O, melts at 0°C, boils at 100°C). A mixture contains two or more substances physically combined with no fixed ratio and properties that vary depending on composition (e.g., saltwater can be more or less salty).
How do I identify whether a mixture is homogeneous or heterogeneous?+
Look at it: if you can see distinct parts or particles (like sand in water, oil floating on water), it is heterogeneous. If it appears uniform throughout with no visible boundaries (like sugar dissolved in water, air), it is homogeneous. Use a magnifying glass if unsure.
What is the Tyndall effect and why is it important?+
The Tyndall effect is the scattering of light by colloidal particles, making the light beam visible when it passes through the mixture (e.g., torch beam visible in milk or fog). It helps distinguish colloids from true solutions, which do not scatter light because their particles are too small.
Which separation technique should I use for sand mixed with salt and water?+
First, use filtration to remove sand (insoluble solid); sand stays on the filter paper while saltwater passes through. Then, use evaporation on the filtrate to remove water, leaving salt crystals behind. Two techniques in sequence are required because sand and salt have different solubilities.
Is dissolving sugar in water a physical or chemical change?+
It is a physical change. Sugar molecules disperse uniformly in water but remain sugar; no new substance forms. You can recover sugar by evaporating the water, proving the change is reversible and the chemical identity is unchanged.
How is a colloid different from a suspension?+
Colloid particles are 1–1000 nanometers, do not settle easily, and scatter light (Tyndall effect). Suspension particles are larger, settle over time when left undisturbed, and can be separated by simple filtration. Milk is a colloid; muddy water is a suspension.
Can air be called a solution? Why or why not?+
Yes, air is a solution — a homogeneous mixture of gases (mainly nitrogen and oxygen) where each gas is uniformly distributed. Solutions need not be liquid; gases dissolving in gases also form solutions, as do some solids in solids (alloys).
What are solute and solvent? Give one example each.+
Solute is the substance that dissolves (usually present in smaller amount); solvent is the substance in which solute dissolves (usually present in larger amount). Example: in saltwater, salt is the solute and water is the solvent.
Why does saltwater boil at a higher temperature than pure water?+
Dissolved salt particles interfere with water molecules escaping into vapour, so more heat energy is needed to make the solution boil. This phenomenon is called boiling point elevation and is a colligative property of solutions.
How can I score full marks in CBSE Class 9 Chemistry Chapter 2 questions?+
Use exact NCERT definitions, give clear examples, label diagrams if asked, and structure long answers in points. Practice worksheets like this one under timed conditions, compare with model answers, and revise mistakes. Consistent practice and self-assessment are key to scoring 90+ in term exams.

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