Class 9 Science Chapter 6: Materials Around Us MCQ Quiz with Solutions

The new CBSE assessment blueprint emphasizes higher-order thinking skills, not rote memorization. Multiple-choice questions in Chapter 6 test your ability to: 1. **Apply properties to real-world scenarios**: Given a material's lustre and density, identify its best use. 2. **Interpret data tables**: Classify substances based on solubility graphs or hardness scales. 3. **Distinguish between physical and chemical properties**: Essential for board exams and competitive exams like JEE Foundation. 4. **Recognize misconceptions**: CBSE exams deliberately include plausible distractors—MCQs train your brain to spot them. MCQs also consume less writing time in board exams. While descriptive answers demand 5–7 minutes, MCQs take 45 seconds if you're confident. Practicing 30 questions builds pattern recognition: you'll instantly recognize phrases like "lustrous metal" or "insoluble in water" and avoid trap answers. Each MCQ in this quiz includes a one-line reasoning line, so you don't just memorize options—you internalize *why* option (C) beats options (A), (B), and (D).

**Q1.** Which property describes how shiny a material appears? (A) Hardness (B) Lustre (C) Density (D) Solubility **Answer: (B) Lustre** Reason: Lustre is the shininess or reflectivity of a surface; metals like gold and silver are lustrous, while wood is not. --- **Q2.** Water is which type of material? (A) Transparent and opaque (B) Transparent (C) Opaque (D) None of these **Answer: (B) Transparent** Reason: Light passes through water without significant scattering, making it transparent; oil blocks light visibility, so it's opaque. --- **Q3.** Which material is an example of a *hard* substance? (A) Cotton (B) Rubber (C) Diamond (D) Plastic **Answer: (C) Diamond** Reason: Diamond is the hardest known natural material; it resists scratching and deformation, unlike soft materials like rubber or cotton. --- **Q4.** Salt is soluble in which liquid? (A) Oil (B) Petrol (C) Water (D) Alcohol (partially) **Answer: (C) Water** Reason: Salt dissolves readily in water due to water's polar nature; it does not dissolve significantly in oils or petrol. --- **Q5.** Density is defined as: (A) Mass ÷ Volume (B) Volume ÷ Mass (C) Mass × Volume (D) Height ÷ Width **Answer: (A) Mass ÷ Volume** Reason: Density measures how much mass is packed into a unit volume; iron is denser than cork because the same volume of iron has more mass. --- **Q6.** Which of the following is *opaque*? (A) Glass (B) Water (C) Frosted glass (D) Clear plastic **Answer: (C) Frosted glass** Reason: Frosted glass has a rough surface that scatters light, blocking clear vision; regular glass is transparent because light passes straight through. --- **Q7.** Metals are generally: (A) Non-lustrous and soft (B) Lustrous and hard (C) Transparent and hard (D) Opaque and liquid **Answer: (B) Lustrous and hard** Reason: Most metals (copper, aluminum, iron) exhibit lustre due to their crystal structure and are mechanically hard—exceptions like sodium are addressed in higher classes. --- **Q8.** Which property makes copper a good choice for electrical wires? (A) Hardness (B) Conductivity (conducts electricity) (C) Transparency (D) Malleability alone **Answer: (B) Conductivity** Reason: Copper's ability to conduct electricity is its primary advantage in wiring; hardness and malleability are secondary benefits. --- **Q9.** A material that does not allow light to pass through is: (A) Translucent (B) Transparent (C) Opaque (D) Reflective **Answer: (C) Opaque** Reason: Opaque materials completely block light transmission; wood, metals, and thick plastics are opaque. --- **Q10.** Which substance is an example of a *soft* material? (A) Steel (B) Lead (C) Glass (D) Wax **Answer: (D) Wax** Reason: Wax deforms easily under pressure without breaking; lead is also soft but wax is more commonly cited in CBSE textbooks as an everyday soft material.

**Q11.** Why is aluminium foil used for food wrapping instead of steel foil? (A) Aluminium is harder than steel. (B) Aluminium is malleable and does not rust easily. (C) Aluminium is cheaper than all metals. (D) Aluminium conducts heat better than steel. **Answer: (B) Aluminium is malleable and does not rust easily.** Reason: Malleability allows thin foil production; aluminium oxide coating prevents rust, unlike steel which corrodes in moisture. --- **Q12.** A substance has a density of 2.5 g/cm³. Which statement is true? (A) It is lighter than water (density 1.0 g/cm³). (B) It will float in water. (C) It will sink in water. (D) Its volume equals its mass numerically. **Answer: (C) It will sink in water.** Reason: Density 2.5 g/cm³ > 1.0 g/cm³ means the substance is denser than water and will sink. --- **Q13.** Cotton cloth is chosen for summer clothing because: (A) It is opaque and reflects heat. (B) It absorbs water and allows evaporative cooling. (C) It is a metal and conducts heat away. (D) It has high lustre. **Answer: (B) It absorbs water and allows evaporative cooling.** Reason: Cotton's porosity absorbs sweat; water evaporation from fabric surface cools the skin—a physical property essential for comfort. --- **Q14.** Which pair of properties best describes *rubber*? (A) Hard and brittle (B) Soft and elastic (C) Hard and elastic (D) Soft and rigid **Answer: (B) Soft and elastic** Reason: Rubber deforms easily (soft) and returns to original shape (elastic); this combination makes it ideal for tyres and gaskets. --- **Q15.** Glass is preferred for windows over plastic because: (A) Glass is harder and does not yellow with age like plastic. (B) Glass is more flexible than plastic. (C) Glass is cheaper than plastic. (D) Glass conducts heat better than plastic. **Answer: (A) Glass is harder and does not yellow with age like plastic.** Reason: Hardness resists scratching; UV stability preserves transparency over decades, whereas acrylic plastics degrade and become opaque. --- **Q16.** A solid substance has the following properties: lustrous, conducts electricity, can be hammered into sheets. It is most likely: (A) A non-metal (B) A metal (C) A ceramic (D) A polymer **Answer: (B) A metal** Reason: Lustre + electrical conductivity + malleability (hammering into sheets) are characteristic properties of metals; non-metals lack electrical conductivity. --- **Q17.** Why are ceramic cups chosen over plastic for serving hot beverages? (A) Ceramics are transparent. (B) Ceramics are poor conductors of heat and do not leach chemicals when hot. (C) Ceramics are more dense than plastic. (D) Ceramics are softer than plastic. **Answer: (B) Ceramics are poor conductors of heat and do not leach chemicals when hot.** Reason: Low thermal conductivity prevents hand burns; ceramics are chemically stable at high temperatures unlike plastics, which may release toxins. --- **Q18.** If a substance is insoluble in water but soluble in petrol, its most likely classification is: (A) Ionic compound (like salt) (B) Polar molecule (like sugar) (C) Non-polar compound (like wax or grease) (D) Metallic compound **Answer: (C) Non-polar compound** Reason: "Like dissolves like"—non-polar substances dissolve in non-polar solvents (petrol); polar substances dissolve in polar solvents (water). --- **Q19.** A material is translucent. This means: (A) Light does not pass through it. (B) Light passes through but the object behind is not clearly visible. (C) Light passes completely and objects are clearly visible. (D) The material is partially liquid. **Answer: (B) Light passes through but the object behind is not clearly visible.** Reason: Translucent materials (frosted glass, greaseproof paper) scatter light; they differ from transparent (clear vision) and opaque (no light). --- **Q20.** Copper is used for water pipes instead of plastic because: (A) Copper is less expensive. (B) Copper is strong, does not degrade under pressure, and is antimicrobial. (C) Copper is transparent. (D) Copper is non-conducting. **Answer: (B) Copper is strong, does not degrade under pressure, and is antimicrobial.** Reason: Mechanical strength withstands water pressure; copper ions naturally prevent bacterial growth—plastic degrades over time and can crack.

**Q21.** **Assertion (A):** Steel is more suitable than aluminium for car bodies in high-temperature environments. **Reason (R):** Aluminium has a lower melting point than steel, causing it to warp at high temperatures. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true. **Answer: (A) Both A and R are true, and R is the correct explanation of A.** Reason: Aluminium melts at ~660°C, steel at ~1370°C; thermal stability directly justifies steel's choice for engine blocks. --- **Q22.** **Assertion (A):** A substance with high density always sinks in water. **Reason (R):** Density alone determines buoyancy; shape and surface area are irrelevant. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) Both A and R are false. **Answer: (C) A is true, but R is false.** Reason: Iron (density 7.8 g/cm³) sinks as a solid but floats in a steel ship due to shape; buoyancy depends on density *and* geometry (Archimedes' principle). --- **Q23.** **Assertion (A):** Rubber tubing is preferred for laboratory use over plastic tubing because rubber is more elastic. **Reason (R):** Elasticity prevents cracks and leakage under repeated pressure cycles. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true. **Answer: (A) Both A and R are true, and R is the correct explanation of A.** Reason: Rubber's elasticity (returns to shape after deformation) prevents fatigue cracks; plastic becomes brittle after repeated stress cycles. --- **Q24.** **Assertion (A):** Gold is more suitable than silver for jewellery because gold is more lustrous. **Reason (R):** Lustre alone determines jewellery selection; cost and durability do not matter. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true. **Answer: (C) A is true, but R is false.** Reason: Gold is chosen for lustre *and* resistance to tarnishing; silver is equally lustrous but oxidizes quickly, making the second reason factually incorrect. --- **Q25.** **Assertion (A):** Sugar dissolves in water but not in petrol because sugar is a polar compound. **Reason (R):** Polar solvents dissolve polar solutes; non-polar solvents dissolve non-polar solutes. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) Both A and R are false. **Answer: (A) Both A and R are true, and R is the correct explanation of A.** Reason: Sugar (C₁₂H₂₂O₁₁) contains many hydroxyl groups making it polar; water is polar, petrol is non-polar—the solubility rule (like dissolves like) explains the observation. --- **Q26.** **Assertion (A):** Transparent glass should be used for building windows, while opaque brick is used for walls. **Reason (R):** Light transmission is the only property that matters in construction. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true. **Answer: (C) A is true, but R is false.** Reason: Glass is chosen for windows primarily for transparency (allowing light and views); however, thermal insulation, strength, and cost also matter—the reason oversimplifies. --- **Q27.** **Assertion (A):** Iron utensils are preferable to tin utensils for cooking despite iron's tendency to rust because iron has better thermal conductivity. **Reason (R):** Thermal conductivity ensures even heat distribution, improving cooking efficiency and food quality. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true. **Answer: (A) Both A and R are true, and R is the correct explanation of A.** Reason: Iron's thermal conductivity (~80 W/m·K) exceeds tin's (~67 W/m·K); better heat distribution prevents hotspots, though rust prevention (seasoning) is a separate maintenance issue. --- **Q28.** **Assertion (A):** A cloth made of nylon is unsuitable for winter wear compared to wool. **Reason (R):** Nylon is a synthetic polymer with low thermal insulation; wool fibres trap air, providing insulation. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) Both A and R are false. **Answer: (A) Both A and R are true, and R is the correct explanation of A.** Reason: Wool's crimped fibres create air pockets (low thermal conductivity ~0.05 W/m·K); nylon is smooth and conducts heat away, making it poor for insulation. --- **Q29.** **Assertion (A):** A substance that is both hard and brittle is suitable for making tools like hammers. **Reason (R):** Brittleness prevents deformation under impact, preserving tool shape. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) Both A and R are false. **Answer: (D) Both A and R are false.** Reason: Hammer heads must be hard *but not brittle*—brittleness causes cracking under impact; steel is hard and ductile (malleable), not brittle, making it ideal for tools. --- **Q30.** **Assertion (A):** Lead is unsuitable for food containers even though it is highly dense and appears inert. **Reason (R):** Lead is toxic and can leach into food over time, especially acidic foods, causing health hazards. (A) Both A and R are true, and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) Both A and R are false. **Answer: (A) Both A and R are true, and R is the correct explanation of A.** Reason: Lead's density and opacity make it physically suitable, but neurotoxic effects outweigh these benefits; acetic acid (in pickled foods) accelerates leaching, making R the correct explanation.

CBSE examiners deliberately plant plausible distractors in MCQs. Here are the five most common traps in Materials Around Us questions: **Trap 1: Confusing Properties with Applications** *Example:* "Why is copper used for electrical wires?" *Trap answer:* "Because copper is hard." (Hardness is irrelevant; conductivity matters.) *How to spot it:* Always ask, "Which property *directly* causes this application?" Write it down before reading options. **Trap 2: Partial Truth (True but Not the Best Answer)** *Example:* "Glass is used for windows because..." *Option A:* "It is hard." (True—glass is hard, but so is steel.) *Option B:* "It is transparent." (Better—allows light in, which steel doesn't.) *How to spot it:* Eliminate options that are *true but incomplete*; choose the **most specific reason**. **Trap 3: Reversing Cause and Effect** *Example:* "Why does a substance sink in water?" *Trap:* "Because it is heavy." (Trap—weight is relative; *density* is the actual cause.) *Correct:* "Because its density is greater than water's density." *How to spot it:* In MCQs on properties, always check if the option uses the correct *property name*, not vague adjectives like "heavy" or "light." **Trap 4: Overgeneralization** *Example:* "All metals are...?" *Trap answer:* "...hard and strong." (Exception: Sodium is soft; mercury is liquid.) *How to spot it:* Watch for words like "all," "always," "never." Class 9 CBSE expects you to know *major exceptions* (sodium, potassium, mercury). **Trap 5: Confusing Transparent, Translucent, and Opaque** *Example:* A frosted glass window. Is it transparent, translucent, or opaque? *Trap:* "Opaque—I can't see clearly." (Wrong—opaque means no light passes; translucent means light passes but image is unclear.) *How to spot it:* Use this flowchart: - Can light pass through? NO → Opaque. - Can light pass through? YES → Can you see a clear image? YES → Transparent. NO → Translucent. **Trap 6: Mixing Up Solubility with Chemical Change** *Example:* "Salt dissolves in water. What happens?" *Trap:* "A chemical reaction occurs; new substances form." (Wrong—dissolution is physical; NaCl and H₂O remain unchanged.) *How to spot it:* Solubility is a *physical property*. No new bonds form; you can recover salt by evaporating water.

CBSE Class 9 Science term tests and competitive exams like KVPY/Olympiad allocate 40–60 minutes for 25–40 MCQs. Poor time management leads to incomplete attempts or careless errors. Here's a battle-tested strategy: **Stage 1: First Pass (Confidence Sorting) — 8 minutes** - Read all questions and mark them as: - **Green (Easy):** You know the answer in ≤20 seconds. (Examples: Q1, Q5, Q10) - **Yellow (Medium):** Requires 45–60 seconds of reasoning. (Examples: Q15, Q18) - **Red (Hard):** Assertion-reason or complex scenarios; skip for now. (Examples: Q25, Q30) - Do NOT answer during this pass. Just mark and move. **Stage 2: Answer Green Questions — 5 minutes** - You'll have ~10–15 green questions at ~30 seconds each. - Avoid second-guessing. If your instinct says (B), write (B). Return only if you finish Stage 2 early. - Expected accuracy: 95%+ **Stage 3: Answer Yellow Questions — 20 minutes** - Start with questions related to *single concepts* (e.g., "Why is copper used for wires?"). - For multi-step problems (density comparisons, solubility predictions), write down the key property first: - "Copper → electrical conductivity → Q12 answer is (B)." - Expected accuracy: 75–85% **Stage 4: Answer Red Questions (Assertion-Reason) — 15 minutes** - Use the flowchart: - Is Assertion true? YES/NO - Is Reason true? YES/NO - Does Reason explain Assertion? YES/NO - Choose (A), (B), (C), or (D). - For Q21–Q30, read the Reason *first*—if it's nonsensical, options (A) and (B) are out. - Expected accuracy: 60–70% (These are intentionally hard.) **Stage 5: Review & Guessing (Last 2–3 minutes)** - If you finish Stage 4 early, go back to yellow/red questions you skipped. - For remaining blanks: Avoid choosing the same letter twice in a row (CBSE answer keys rarely have three (A)'s or (B)'s consecutively). If stuck, choose the *longest option*—it's usually more detailed. **Pro Tips:** 1. **Mark on paper:** Write "G," "Y," "R" next to question numbers; don't rely on memory. 2. **Avoid backtracking:** Once you answer a green or yellow question, move on. Backtracking wastes 2–3 minutes per question. 3. **For assertion-reason MCQs, test the reason first:** If the reason is illogical or incorrect, eliminate (A) and (B) immediately—saves 15 seconds. 4. **Read *all* options before answering:** Sometimes option (D) is "All of the above" or "None of these," which changes your choice. **Expected Result with This Strategy:** - 30-question test in 45 minutes → ~35–38 correct (85–90%) - Follow this pattern three times before your exam for muscle memory.

This 30-question quiz mirrors CBSE's actual assessment pattern. But simply answering questions won't prepare you thoroughly. Here's a structured approach: **Day 1–2: Easy MCQs (Q1–Q10)** - Spend 20 minutes answering all 10 questions without external help. - Note your score out of 10. - Read the one-line reason for *every* answer, even the ones you got right—the explanation cements the concept. - Identify your weakness (e.g., "I confused lustre with colour") and revisit NCERT Section 6.1 on properties. **Day 3–4: Medium MCQs (Q11–Q20)** - Spend 30 minutes on these application-based questions. - For each incorrect answer, write a 2–3 sentence explanation of why the correct option is better. Example: - Q15 wrong answer: "Glass is more flexible than plastic." My correction: "Glass is harder and UV-stable, not flexible—plastic is actually more flexible but degrades faster." - This writing reinforces your understanding. **Day 5–6: Hard Assertion-Reason MCQs (Q21–Q30)** - Spend 40 minutes. These are intentionally challenging. - Use the flowchart provided in the time-management section. - For each incorrect answer, identify whether you got the Assertion or the Reason wrong—it pinpoints conceptual gaps. **Day 7: Full Mock Test (All 30 in 45 Minutes)** - Simulate exam conditions: no NCERT reference, no pauses between questions. - Time yourself strictly. - Review immediately and identify patterns in your errors (e.g., "I always confuse density and mass"). - Target: 26/30 (87%). **Weekly Reinforcement:** - Revisit the wrong questions every 3–4 days using spaced repetition. - Create flashcards for confusing pairs (transparent vs. translucent, hard vs. brittle). - Watch video explanations at cbsetutor.ai for your three weakest questions; the visual breakdown solidifies understanding faster than text. This structured approach ensures you don't just memorize answers—you *internalize* the reasoning, making you confident in board exams and competitive tests.