Combustion and Flame – Interactive Questions<\/title>\n <style>\n * {\n margin: 0;\n padding: 0;\n box-sizing: border-box;\n font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;\n }\n\n body {\n background: linear-gradient(135deg, #1a2a6c, #b21f1f, #fdbb2d);\n background-size: 400% 400%;\n animation: gradient 15s ease infinite;\n color: #fff;\n min-height: 100vh;\n padding: 40px 20px;\n }\n\n @keyframes gradient {\n 0% { background-position: 0% 50%; }\n 50% { background-position: 100% 50%; }\n 100% { background-position: 0% 50%; }\n }\n\n .container {\n max-width: 1200px;\n margin: 0 auto;\n }\n\n .header {\n text-align: center;\n margin-bottom: 50px;\n padding: 30px;\n background: rgba(255, 255, 255, 0.1);\n backdrop-filter: blur(10px);\n border-radius: 20px;\n box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);\n border: 1px solid rgba(255, 255, 255, 0.2);\n }\n\n .header h1 {\n font-size: 3.5rem;\n margin-bottom: 15px;\n background: linear-gradient(45deg, #FFD700, #FFA500, #FF8C00);\n -webkit-background-clip: text;\n -webkit-text-fill-color: transparent;\n text-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);\n }\n\n .header p {\n font-size: 1.3rem;\n opacity: 0.9;\n max-width: 800px;\n margin: 0 auto;\n }\n\n .questions-grid {\n display: grid;\n grid-template-columns: repeat(auto-fill, minmax(550px, 1fr));\n gap: 30px;\n }\n\n .question-card {\n background: rgba(255, 255, 255, 0.1);\n backdrop-filter: blur(10px);\n border-radius: 20px;\n padding: 30px;\n box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);\n border: 1px solid rgba(255, 255, 255, 0.2);\n transition: all 0.4s ease;\n cursor: pointer;\n position: relative;\n overflow: hidden;\n }\n\n .question-card::before {\n content: '';\n position: absolute;\n top: 0;\n left: 0;\n width: 100%;\n height: 5px;\n background: linear-gradient(90deg, #FF6B6B, #FF8E53, #FFD166, #06D6A0, #118AB2, #073B4C);\n }\n\n .question-card:hover {\n transform: translateY(-10px);\n box-shadow: 0 15px 40px rgba(0, 0, 0, 0.3);\n background: rgba(255, 255, 255, 0.15);\n }\n\n .question-number {\n display: inline-block;\n background: linear-gradient(45deg, #FF6B6B, #FF8E53);\n color: white;\n padding: 8px 20px;\n border-radius: 50px;\n font-weight: bold;\n margin-bottom: 20px;\n box-shadow: 0 5px 15px rgba(255, 107, 107, 0.4);\n }\n\n .question-text {\n font-size: 1.3rem;\n line-height: 1.6;\n margin-bottom: 25px;\n color: #000000;\n font-weight: 600;\n }\n\n .toggle-answer {\n background: linear-gradient(45deg, #06D6A0, #118AB2);\n color: white;\n border: none;\n padding: 12px 25px;\n border-radius: 50px;\n font-weight: bold;\n cursor: pointer;\n transition: all 0.3s ease;\n display: flex;\n align-items: center;\n justify-content: center;\n gap: 10px;\n box-shadow: 0 5px 15px rgba(6, 214, 160, 0.4);\n width: 100%;\n }\n\n .toggle-answer:hover {\n transform: scale(1.05);\n box-shadow: 0 8px 20px rgba(6, 214, 160, 0.6);\n }\n\n .answer-content {\n max-height: 0;\n overflow: hidden;\n transition: max-height 0.5s ease;\n background: rgba(0, 0, 0, 0.2);\n border-radius: 15px;\n padding: 0 25px;\n margin-top: 0;\n }\n\n .answer-content.show {\n max-height: 2000px;\n padding: 25px;\n margin-top: 25px;\n }\n\n .answer-text {\n font-size: 1.1rem;\n line-height: 1.7;\n color: #333333;\n }\n\n .answer-text strong {\n color: #FFD700;\n }\n\n .flame-icon {\n display: inline-block;\n animation: flicker 2s infinite alternate;\n font-size: 1.5rem;\n }\n\n @keyframes flicker {\n 0%, 100% { opacity: 1; }\n 50% { opacity: 0.7; }\n }\n\n .footer {\n text-align: center;\n margin-top: 60px;\n padding: 20px;\n font-size: 1.1rem;\n opacity: 0.8;\n }\n\n @media (max-width: 768px) {\n .questions-grid {\n grid-template-columns: 1fr;\n }\n \n .header h1 {\n font-size: 2.5rem;\n }\n }\n <\/style>\n<\/head>\n<body>\n <div class=\"container\">\n <div class=\"header\">\n <h1><span class=\"flame-icon\">\ud83d\udd25<\/span> Combustion & Flame <span class=\"flame-icon\">\ud83d\udd25<\/span><\/h1>\n <p>Class 8 Science – Interactive Conceptual Questions<\/p>\n <p style=\"margin-top: 15px; font-size: 1.1rem;\">Click on “Show Answer” to reveal detailed explanations<\/p>\n <\/div>\n\n <div class=\"questions-grid\">\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 1<\/div>\n <div class=\"question-text\">A student conducted an experiment with three candles of identical size placed in different conditions. Candle A burned for 25 minutes, Candle B for 2 minutes, and Candle C for 4 minutes. Explain the scientific principles behind these observations.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Scientific Explanation:<\/strong> This experiment demonstrates that combustion requires oxygen. Candle A burned longest with unlimited oxygen. Candles B and C extinguished due to oxygen depletion. Burning time is proportional to available oxygen volume.<br><br>\n <strong>Mathematical Analysis:<\/strong> Candle B (500ml jar): 2 minutes, Candle C (1000ml jar): 4 minutes. This shows double volume = double burning time.<br><br>\n <strong>Conceptual Depth:<\/strong> The candle consumes oxygen and produces CO\u2082. Even with CO\u2082 accumulation, oxygen depletion is the limiting factor. This demonstrates the fire triangle – removing oxygen breaks combustion.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 2<\/div>\n <div class=\"question-text\">A chemistry teacher showed three different flames: blue from Bunsen burner, yellow from candle, and almost invisible from spirit lamp. Explain the scientific reasons for these color variations.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Flame Color Science:<\/strong> Color depends on oxygen supply and combustion completeness.<br><br>\n <strong>Bunsen Burner (Blue):<\/strong> Complete combustion, high temperature (1300\u00b0C+), efficient burning, carbon completely combusts to CO\u2082.<br><br>\n <strong>Candle (Yellow):<\/strong> Incomplete combustion, limited oxygen, yellow from incandescent carbon particles, produces soot and CO.<br><br>\n <strong>Spirit Lamp (Invisible):<\/strong> Nearly complete combustion, clean burning fuel, few carbon particles, blue hue visible in darkness.<br><br>\n <strong>Energy Analysis:<\/strong> Blue flames = more heat, less light; Yellow flames = less heat, more light.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 3<\/div>\n <div class=\"question-text\">A forest fire started and spread rapidly despite no wind, creating its own wind patterns. Explain the physics and chemistry behind this rapid spread and self-generated weather system.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Combustion Chain Reaction:<\/strong> Dry leaves reach ignition temperature (~300\u00b0C), fire spreads through radiant heat, creates convection currents.<br><br>\n <strong>Fire-Generated Winds:<\/strong><br>\n – Temperature gradient: Fire heats air \u2192 less dense \u2192 rises rapidly \u2192 low pressure at ground \u2192 cooler air rushes in \u2192 feeds oxygen to fire<br>\n – Fire Triangle Optimization: Abundant dry fuel + self-generated oxygen supply + heat feedback loop<br>\n – Pyrolysis: Heat vaporizes wood compounds \u2192 gases ignite first \u2192 heats solid fuel further \u2192 accelerating combustion<br><br>\n <strong>Mathematical Insight:<\/strong> Fire spread rate \u221d (Fuel \u00d7 Temperature \u00d7 Oxygen) \u00f7 Humidity\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 4<\/div>\n <div class=\"question-text\">Four fuels were tested with 1g each producing different temperature rises in water. Calculate approximate calorific values and analyze which fuel is most efficient for domestic and industrial use.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Calorific Value Calculation:<\/strong> Heat = mass of water \u00d7 specific heat \u00d7 \u0394T<br><br>\n <strong>Results:<\/strong><br>\n – Fuel A: 45\u00b0C rise = 18.8 kJ\/g<br>\n – Fuel B: 55\u00b0C rise = 23.0 kJ\/g<br>\n – Fuel C: 35\u00b0C rise = 14.6 kJ\/g<br>\n – Fuel D: 25\u00b0C rise + soot = 10.5 kJ\/g (poor efficiency)<br><br>\n <strong>Recommendations:<\/strong><br>\n – Domestic use: Fuel B (highest calorific value, clean combustion)<br>\n – Industrial use: Fuel A or B depending on cost and availability<br><br>\n <strong>Scientific Justification:<\/strong> Ideal fuel has high calorific value, clean combustion, moderate ignition temperature, safe handling.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 5<\/div>\n <div class=\"question-text\">A farmer stored moist hay in a sealed barn. After three days, it caught fire without external ignition. Investigate this spontaneous combustion phenomenon.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Spontaneous Combustion Stages:<\/strong><br><br>\n <strong>Stage 1: Biological Activity (Day 1)<\/strong><br>\n – Microorganisms respire in moist hay<br>\n – Biological oxidation produces heat<br>\n – Confined space prevents heat dissipation<br><br>\n <strong>Stage 2: Chemical Oxidation (Day 2)<\/strong><br>\n – Temperature rises to 40-60\u00b0C<br>\n – Direct oxidation of hay components accelerates<br>\n – More exothermic heat production<br><br>\n <strong>Stage 3: Thermal Runaway (Day 3)<\/strong><br>\n – At 80-100\u00b0C, pyrolysis begins<br>\n – Volatile gases release<br>\n – At 150-200\u00b0C, gases auto-ignite<br><br>\n <strong>Critical Factors:<\/strong> Moisture, insulation, fuel arrangement, limited oxygen supply<br>\n <strong>Prevention:<\/strong> Store hay dry, ensure ventilation, monitor temperature.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 6<\/div>\n <div class=\"question-text\">In a closed room (4m\u00d74m\u00d73m), a kerosene lamp burned for 6 hours before extinguishing. Calculate oxygen consumed and explain why it extinguished with 78% nitrogen remaining.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Room Volume:<\/strong> 4\u00d74\u00d73 = 48 m\u00b3 = 48,000 liters<br><br>\n <strong>Oxygen Available:<\/strong> 21% of 48,000 = 10,080 liters initially<br><br>\n <strong>Oxygen Consumption:<\/strong><br>\n – Kerosene combustion: 2C\u2081\u2082H\u2082\u2086 + 37O\u2082 \u2192 24CO\u2082 + 26H\u2082O<br>\n – Typical consumption: 10-15 liters O\u2082\/hour<br>\n – For 6 hours: 6\u00d712.5 = 75 liters consumed<br><br>\n <strong>The Paradox Explanation:<\/strong><br>\n Flame extinguished not because all oxygen was consumed, but because oxygen concentration dropped below 15% (minimum for sustained combustion). Nitrogen acted as diluent, reducing oxygen partial pressure and slowing combustion until it could no longer sustain the flame.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 7<\/div>\n <div class=\"question-text\">Analyze why a matchstick ignites only when struck against the specific side of the matchbox, explaining the chemistry behind each component’s role.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Match Head Composition:<\/strong><br>\n – Potassium chlorate (KClO\u2083) – Oxygen donor<br>\n – Sulfur\/antimony sulfide – Fuel<br>\n – Glass powder – Friction generator<br>\n – Glue – Binder<br><br>\n <strong>Matchbox Side Composition:<\/strong><br>\n – Red phosphorus – Less stable allotrope<br>\n – Glass powder – Friction<br>\n – Glue – Binder<br><br>\n <strong>Ignition Chemistry:<\/strong><br>\n 1. Friction heat (200-300\u00b0C) converts red phosphorus to white phosphorus<br>\n 2. White phosphorus ignites spontaneously in air<br>\n 3. Activates potassium chlorate decomposition: 2KClO\u2083 \u2192 2KCl + 3O\u2082<br>\n 4. Oxygen released supports sulfur combustion: S + O\u2082 \u2192 SO\u2082<br>\n 5. Chain reaction ignites wooden stick\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 8<\/div>\n <div class=\"question-text\">Three fire extinguishers were tested on identical electrical fires with different results. Analyze the scientific principles behind each extinguisher’s performance.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Type A (CO\u2082) – 8 seconds:<\/strong><br>\n – Mechanism: Smothering by displacing oxygen + cooling<br>\n – CO\u2082 density (1.98 g\/L) > air (1.29 g\/L) – blankets fire<br>\n – Limitation: Wind can disperse CO\u2082<br><br>\n <strong>Type B (Dry Powder) – 6 seconds (Most Effective):<\/strong><br>\n – Mechanism: Chemical inhibition + smothering<br>\n – Powder forms radical traps breaking combustion chain<br>\n – Creates barrier between fuel and oxygen<br>\n – ABC powder works on all fire types<br><br>\n <strong>Type C (Water Mist) – Failed:<\/strong><br>\n – Reason: Water conducts electricity – electrocution risk<br>\n – Electrical fires require non-conductive agents<br>\n – Water can spread electrical current\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 9<\/div>\n <div class=\"question-text\">Predict and explain how a candle would burn in microgravity environment of International Space Station compared to Earth’s gravity-based burning.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>On Earth:<\/strong><br>\n – Flame shape: Teardrop (hot gases rise by convection)<br>\n – Color: Blue at bottom, yellow on top<br>\n – Mechanism: Gravity-driven convection brings oxygen<br><br>\n <strong>In Space (Microgravity):<\/strong><br>\n – Flame shape: Spherical (no “up” direction)<br>\n – Color: Consistent blue throughout<br>\n – Temperature: Lower (200-500\u00b0C vs 800-1400\u00b0C)<br>\n – Combustion: More complete but slower<br><br>\n <strong>Scientific Explanation:<\/strong><br>\n – No buoyancy = no convection = oxygen reaches flame only by diffusion<br>\n – Diffusion slower than convection = lower temperature<br>\n – Complete combustion because soot particles don’t rise away = more time to burn<br>\n – Flame appears dim blue because no incandescent soot particles\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 10<\/div>\n <div class=\"question-text\">A car engine produces different exhaust compositions at different speeds. Explain the combustion chemistry behind these variations and identify the most environmentally friendly condition.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Idle Speed (Rich Mixture):<\/strong><br>\n – Fuel-air ratio: Excess fuel, limited oxygen<br>\n – Chemistry: C\u2088H\u2081\u2088 + 8.5O\u2082 \u2192 8CO + 9H\u2082O (incomplete)<br>\n – Results: High CO, unburnt hydrocarbons, soot<br><br>\n <strong>Optimal Speed (Stoichiometric):<\/strong><br>\n – Perfect fuel-air ratio (1:14.7 for petrol)<br>\n – Chemistry: C\u2088H\u2081\u2088 + 12.5O\u2082 \u2192 8CO\u2082 + 9H\u2082O (complete)<br>\n – Results: Maximum efficiency, minimal pollution<br><br>\n <strong>High Speed (Lean Mixture + High Temperature):<\/strong><br>\n – Excess air, high compression temperature<br>\n – Chemistry: N\u2082 + O\u2082 \u2192 2NO (at >1300\u00b0C)<br>\n – Results: Nitrogen oxides formation<br><br>\n <strong>Environmental Recommendation:<\/strong> Optimal speed is most eco-friendly due to complete combustion and minimal harmful emissions.\n <\/div>\n <\/div>\n <\/div>\n\n \n \n\n <\/div>\n\n <div class=\"footer\">\n <p>Class 8 Science – Combustion and Flame | Interactive Questions<\/p>\n <p style=\"margin-top: 10px;\">\ud83d\udd25 Click to reveal answers \ud83d\udd25<\/p>\n <\/div>\n <\/div>\n\n <script>\n document.addEventListener('DOMContentLoaded', function() {\n const toggleButtons = document.querySelectorAll('.toggle-answer');\n \n toggleButtons.forEach(button => {\n button.addEventListener('click', function() {\n const answerContent = this.nextElementSibling;\n const isShowing = answerContent.classList.contains('show');\n \n \/\/ Close all other answers\n document.querySelectorAll('.answer-content').forEach(content => {\n content.classList.remove('show');\n });\n \n document.querySelectorAll('.toggle-answer').forEach(btn => {\n 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Interactive Conceptual Questions Click on “Show Answer” to reveal detailed explanations Question 1 A student conducted an experiment with three candles of identical size placed in different conditions. Candle A burned for 25 minutes, Candle B for 2 minutes, and […]<\/p>\n","protected":false},"author":1,"featured_media":162789,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"https:\/\/manishchandra.org\/doc\/webtext\/energetics\/CE-images\/candle_flame.jpg","fifu_image_alt":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-162785","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","cat-1-id","has_thumb"],"yoast_head":"\n<title>Class 8 Science: Combustion and Flame Questions - Gyankatta<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/news.gyankatta.org\/?p=162785\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Class 8 Science: Combustion and Flame Questions - Gyankatta\" \/>\n<meta property=\"og:description\" content=\"Combustion and Flame – Interactive Questions \ud83d\udd25 Combustion & Flame \ud83d\udd25 Class 8 Science – Interactive Conceptual Questions Click on “Show Answer” to reveal detailed explanations Question 1 A student conducted an experiment with three candles of identical size placed in different conditions. 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Candle A burned for 25 minutes, Candle B for 2 minutes, and […]","og_url":"https:\/\/news.gyankatta.org\/?p=162785","og_site_name":"Gyankatta","article_published_time":"2025-10-21T04:22:59+00:00","article_modified_time":"2025-10-21T08:58:56+00:00","og_image":[{"url":"https:\/\/manishchandra.org\/doc\/webtext\/energetics\/CE-images\/candle_flame.jpg","type":"","width":"","height":""}],"author":"sBagul","twitter_card":"summary_large_image","twitter_image":"https:\/\/manishchandra.org\/doc\/webtext\/energetics\/CE-images\/candle_flame.jpg","twitter_misc":{"Written by":"sBagul","Est. reading time":"7 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/news.gyankatta.org\/?p=162785#article","isPartOf":{"@id":"https:\/\/news.gyankatta.org\/?p=162785"},"author":{"name":"sBagul","@id":"https:\/\/news.gyankatta.org\/#\/schema\/person\/ba6f7a4ee74e137c4c2b2c991b4f28e9"},"headline":"Class 8 Science: Combustion and Flame Questions","datePublished":"2025-10-21T04:22:59+00:00","dateModified":"2025-10-21T08:58:56+00:00","mainEntityOfPage":{"@id":"https:\/\/news.gyankatta.org\/?p=162785"},"wordCount":1316,"commentCount":0,"image":{"@id":"https:\/\/news.gyankatta.org\/?p=162785#primaryimage"},"thumbnailUrl":"https:\/\/manishchandra.org\/doc\/webtext\/energetics\/CE-images\/candle_flame.jpg","inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/news.gyankatta.org\/?p=162785#respond"]}]},{"@type":"WebPage","@id":"https:\/\/news.gyankatta.org\/?p=162785","url":"https:\/\/news.gyankatta.org\/?p=162785","name":"Class 8 Science: Combustion and Flame Questions - 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{"id":162785,"date":"2025-10-21T04:22:59","date_gmt":"2025-10-21T04:22:59","guid":{"rendered":"https:\/\/news.gyankatta.org\/?p=162785"},"modified":"2025-10-21T08:58:56","modified_gmt":"2025-10-21T08:58:56","slug":"class-8-science-combustion-and-flame-questions","status":"publish","type":"post","link":"https:\/\/news.gyankatta.org\/?p=162785","title":{"rendered":"Class 8 Science: Combustion and Flame Questions"},"content":{"rendered":"\n

<\/p>\n\n\n\n\n\n\n \n \n Combustion and Flame – Interactive Questions<\/title>\n <style>\n * {\n margin: 0;\n padding: 0;\n box-sizing: border-box;\n font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;\n }\n\n body {\n background: linear-gradient(135deg, #1a2a6c, #b21f1f, #fdbb2d);\n background-size: 400% 400%;\n animation: gradient 15s ease infinite;\n color: #fff;\n min-height: 100vh;\n padding: 40px 20px;\n }\n\n @keyframes gradient {\n 0% { background-position: 0% 50%; }\n 50% { background-position: 100% 50%; }\n 100% { background-position: 0% 50%; }\n }\n\n .container {\n max-width: 1200px;\n margin: 0 auto;\n }\n\n .header {\n text-align: center;\n margin-bottom: 50px;\n padding: 30px;\n background: rgba(255, 255, 255, 0.1);\n backdrop-filter: blur(10px);\n border-radius: 20px;\n box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);\n border: 1px solid rgba(255, 255, 255, 0.2);\n }\n\n .header h1 {\n font-size: 3.5rem;\n margin-bottom: 15px;\n background: linear-gradient(45deg, #FFD700, #FFA500, #FF8C00);\n -webkit-background-clip: text;\n -webkit-text-fill-color: transparent;\n text-shadow: 0 5px 15px rgba(0, 0, 0, 0.3);\n }\n\n .header p {\n font-size: 1.3rem;\n opacity: 0.9;\n max-width: 800px;\n margin: 0 auto;\n }\n\n .questions-grid {\n display: grid;\n grid-template-columns: repeat(auto-fill, minmax(550px, 1fr));\n gap: 30px;\n }\n\n .question-card {\n background: rgba(255, 255, 255, 0.1);\n backdrop-filter: blur(10px);\n border-radius: 20px;\n padding: 30px;\n box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);\n border: 1px solid rgba(255, 255, 255, 0.2);\n transition: all 0.4s ease;\n cursor: pointer;\n position: relative;\n overflow: hidden;\n }\n\n .question-card::before {\n content: '';\n position: absolute;\n top: 0;\n left: 0;\n width: 100%;\n height: 5px;\n background: linear-gradient(90deg, #FF6B6B, #FF8E53, #FFD166, #06D6A0, #118AB2, #073B4C);\n }\n\n .question-card:hover {\n transform: translateY(-10px);\n box-shadow: 0 15px 40px rgba(0, 0, 0, 0.3);\n background: rgba(255, 255, 255, 0.15);\n }\n\n .question-number {\n display: inline-block;\n background: linear-gradient(45deg, #FF6B6B, #FF8E53);\n color: white;\n padding: 8px 20px;\n border-radius: 50px;\n font-weight: bold;\n margin-bottom: 20px;\n box-shadow: 0 5px 15px rgba(255, 107, 107, 0.4);\n }\n\n .question-text {\n font-size: 1.3rem;\n line-height: 1.6;\n margin-bottom: 25px;\n color: #000000;\n font-weight: 600;\n }\n\n .toggle-answer {\n background: linear-gradient(45deg, #06D6A0, #118AB2);\n color: white;\n border: none;\n padding: 12px 25px;\n border-radius: 50px;\n font-weight: bold;\n cursor: pointer;\n transition: all 0.3s ease;\n display: flex;\n align-items: center;\n justify-content: center;\n gap: 10px;\n box-shadow: 0 5px 15px rgba(6, 214, 160, 0.4);\n width: 100%;\n }\n\n .toggle-answer:hover {\n transform: scale(1.05);\n box-shadow: 0 8px 20px rgba(6, 214, 160, 0.6);\n }\n\n .answer-content {\n max-height: 0;\n overflow: hidden;\n transition: max-height 0.5s ease;\n background: rgba(0, 0, 0, 0.2);\n border-radius: 15px;\n padding: 0 25px;\n margin-top: 0;\n }\n\n .answer-content.show {\n max-height: 2000px;\n padding: 25px;\n margin-top: 25px;\n }\n\n .answer-text {\n font-size: 1.1rem;\n line-height: 1.7;\n color: #333333;\n }\n\n .answer-text strong {\n color: #FFD700;\n }\n\n .flame-icon {\n display: inline-block;\n animation: flicker 2s infinite alternate;\n font-size: 1.5rem;\n }\n\n @keyframes flicker {\n 0%, 100% { opacity: 1; }\n 50% { opacity: 0.7; }\n }\n\n .footer {\n text-align: center;\n margin-top: 60px;\n padding: 20px;\n font-size: 1.1rem;\n opacity: 0.8;\n }\n\n @media (max-width: 768px) {\n .questions-grid {\n grid-template-columns: 1fr;\n }\n \n .header h1 {\n font-size: 2.5rem;\n }\n }\n <\/style>\n<\/head>\n<body>\n <div class=\"container\">\n <div class=\"header\">\n <h1><span class=\"flame-icon\">\ud83d\udd25<\/span> Combustion & Flame <span class=\"flame-icon\">\ud83d\udd25<\/span><\/h1>\n <p>Class 8 Science – Interactive Conceptual Questions<\/p>\n <p style=\"margin-top: 15px; font-size: 1.1rem;\">Click on “Show Answer” to reveal detailed explanations<\/p>\n <\/div>\n\n <div class=\"questions-grid\">\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 1<\/div>\n <div class=\"question-text\">A student conducted an experiment with three candles of identical size placed in different conditions. Candle A burned for 25 minutes, Candle B for 2 minutes, and Candle C for 4 minutes. Explain the scientific principles behind these observations.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Scientific Explanation:<\/strong> This experiment demonstrates that combustion requires oxygen. Candle A burned longest with unlimited oxygen. Candles B and C extinguished due to oxygen depletion. Burning time is proportional to available oxygen volume.<br><br>\n <strong>Mathematical Analysis:<\/strong> Candle B (500ml jar): 2 minutes, Candle C (1000ml jar): 4 minutes. This shows double volume = double burning time.<br><br>\n <strong>Conceptual Depth:<\/strong> The candle consumes oxygen and produces CO\u2082. Even with CO\u2082 accumulation, oxygen depletion is the limiting factor. This demonstrates the fire triangle – removing oxygen breaks combustion.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 2<\/div>\n <div class=\"question-text\">A chemistry teacher showed three different flames: blue from Bunsen burner, yellow from candle, and almost invisible from spirit lamp. Explain the scientific reasons for these color variations.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Flame Color Science:<\/strong> Color depends on oxygen supply and combustion completeness.<br><br>\n <strong>Bunsen Burner (Blue):<\/strong> Complete combustion, high temperature (1300\u00b0C+), efficient burning, carbon completely combusts to CO\u2082.<br><br>\n <strong>Candle (Yellow):<\/strong> Incomplete combustion, limited oxygen, yellow from incandescent carbon particles, produces soot and CO.<br><br>\n <strong>Spirit Lamp (Invisible):<\/strong> Nearly complete combustion, clean burning fuel, few carbon particles, blue hue visible in darkness.<br><br>\n <strong>Energy Analysis:<\/strong> Blue flames = more heat, less light; Yellow flames = less heat, more light.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 3<\/div>\n <div class=\"question-text\">A forest fire started and spread rapidly despite no wind, creating its own wind patterns. Explain the physics and chemistry behind this rapid spread and self-generated weather system.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Combustion Chain Reaction:<\/strong> Dry leaves reach ignition temperature (~300\u00b0C), fire spreads through radiant heat, creates convection currents.<br><br>\n <strong>Fire-Generated Winds:<\/strong><br>\n – Temperature gradient: Fire heats air \u2192 less dense \u2192 rises rapidly \u2192 low pressure at ground \u2192 cooler air rushes in \u2192 feeds oxygen to fire<br>\n – Fire Triangle Optimization: Abundant dry fuel + self-generated oxygen supply + heat feedback loop<br>\n – Pyrolysis: Heat vaporizes wood compounds \u2192 gases ignite first \u2192 heats solid fuel further \u2192 accelerating combustion<br><br>\n <strong>Mathematical Insight:<\/strong> Fire spread rate \u221d (Fuel \u00d7 Temperature \u00d7 Oxygen) \u00f7 Humidity\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 4<\/div>\n <div class=\"question-text\">Four fuels were tested with 1g each producing different temperature rises in water. Calculate approximate calorific values and analyze which fuel is most efficient for domestic and industrial use.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Calorific Value Calculation:<\/strong> Heat = mass of water \u00d7 specific heat \u00d7 \u0394T<br><br>\n <strong>Results:<\/strong><br>\n – Fuel A: 45\u00b0C rise = 18.8 kJ\/g<br>\n – Fuel B: 55\u00b0C rise = 23.0 kJ\/g<br>\n – Fuel C: 35\u00b0C rise = 14.6 kJ\/g<br>\n – Fuel D: 25\u00b0C rise + soot = 10.5 kJ\/g (poor efficiency)<br><br>\n <strong>Recommendations:<\/strong><br>\n – Domestic use: Fuel B (highest calorific value, clean combustion)<br>\n – Industrial use: Fuel A or B depending on cost and availability<br><br>\n <strong>Scientific Justification:<\/strong> Ideal fuel has high calorific value, clean combustion, moderate ignition temperature, safe handling.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 5<\/div>\n <div class=\"question-text\">A farmer stored moist hay in a sealed barn. After three days, it caught fire without external ignition. Investigate this spontaneous combustion phenomenon.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Spontaneous Combustion Stages:<\/strong><br><br>\n <strong>Stage 1: Biological Activity (Day 1)<\/strong><br>\n – Microorganisms respire in moist hay<br>\n – Biological oxidation produces heat<br>\n – Confined space prevents heat dissipation<br><br>\n <strong>Stage 2: Chemical Oxidation (Day 2)<\/strong><br>\n – Temperature rises to 40-60\u00b0C<br>\n – Direct oxidation of hay components accelerates<br>\n – More exothermic heat production<br><br>\n <strong>Stage 3: Thermal Runaway (Day 3)<\/strong><br>\n – At 80-100\u00b0C, pyrolysis begins<br>\n – Volatile gases release<br>\n – At 150-200\u00b0C, gases auto-ignite<br><br>\n <strong>Critical Factors:<\/strong> Moisture, insulation, fuel arrangement, limited oxygen supply<br>\n <strong>Prevention:<\/strong> Store hay dry, ensure ventilation, monitor temperature.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 6<\/div>\n <div class=\"question-text\">In a closed room (4m\u00d74m\u00d73m), a kerosene lamp burned for 6 hours before extinguishing. Calculate oxygen consumed and explain why it extinguished with 78% nitrogen remaining.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Room Volume:<\/strong> 4\u00d74\u00d73 = 48 m\u00b3 = 48,000 liters<br><br>\n <strong>Oxygen Available:<\/strong> 21% of 48,000 = 10,080 liters initially<br><br>\n <strong>Oxygen Consumption:<\/strong><br>\n – Kerosene combustion: 2C\u2081\u2082H\u2082\u2086 + 37O\u2082 \u2192 24CO\u2082 + 26H\u2082O<br>\n – Typical consumption: 10-15 liters O\u2082\/hour<br>\n – For 6 hours: 6\u00d712.5 = 75 liters consumed<br><br>\n <strong>The Paradox Explanation:<\/strong><br>\n Flame extinguished not because all oxygen was consumed, but because oxygen concentration dropped below 15% (minimum for sustained combustion). Nitrogen acted as diluent, reducing oxygen partial pressure and slowing combustion until it could no longer sustain the flame.\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 7<\/div>\n <div class=\"question-text\">Analyze why a matchstick ignites only when struck against the specific side of the matchbox, explaining the chemistry behind each component’s role.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Match Head Composition:<\/strong><br>\n – Potassium chlorate (KClO\u2083) – Oxygen donor<br>\n – Sulfur\/antimony sulfide – Fuel<br>\n – Glass powder – Friction generator<br>\n – Glue – Binder<br><br>\n <strong>Matchbox Side Composition:<\/strong><br>\n – Red phosphorus – Less stable allotrope<br>\n – Glass powder – Friction<br>\n – Glue – Binder<br><br>\n <strong>Ignition Chemistry:<\/strong><br>\n 1. Friction heat (200-300\u00b0C) converts red phosphorus to white phosphorus<br>\n 2. White phosphorus ignites spontaneously in air<br>\n 3. Activates potassium chlorate decomposition: 2KClO\u2083 \u2192 2KCl + 3O\u2082<br>\n 4. Oxygen released supports sulfur combustion: S + O\u2082 \u2192 SO\u2082<br>\n 5. Chain reaction ignites wooden stick\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 8<\/div>\n <div class=\"question-text\">Three fire extinguishers were tested on identical electrical fires with different results. Analyze the scientific principles behind each extinguisher’s performance.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Type A (CO\u2082) – 8 seconds:<\/strong><br>\n – Mechanism: Smothering by displacing oxygen + cooling<br>\n – CO\u2082 density (1.98 g\/L) > air (1.29 g\/L) – blankets fire<br>\n – Limitation: Wind can disperse CO\u2082<br><br>\n <strong>Type B (Dry Powder) – 6 seconds (Most Effective):<\/strong><br>\n – Mechanism: Chemical inhibition + smothering<br>\n – Powder forms radical traps breaking combustion chain<br>\n – Creates barrier between fuel and oxygen<br>\n – ABC powder works on all fire types<br><br>\n <strong>Type C (Water Mist) – Failed:<\/strong><br>\n – Reason: Water conducts electricity – electrocution risk<br>\n – Electrical fires require non-conductive agents<br>\n – Water can spread electrical current\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 9<\/div>\n <div class=\"question-text\">Predict and explain how a candle would burn in microgravity environment of International Space Station compared to Earth’s gravity-based burning.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>On Earth:<\/strong><br>\n – Flame shape: Teardrop (hot gases rise by convection)<br>\n – Color: Blue at bottom, yellow on top<br>\n – Mechanism: Gravity-driven convection brings oxygen<br><br>\n <strong>In Space (Microgravity):<\/strong><br>\n – Flame shape: Spherical (no “up” direction)<br>\n – Color: Consistent blue throughout<br>\n – Temperature: Lower (200-500\u00b0C vs 800-1400\u00b0C)<br>\n – Combustion: More complete but slower<br><br>\n <strong>Scientific Explanation:<\/strong><br>\n – No buoyancy = no convection = oxygen reaches flame only by diffusion<br>\n – Diffusion slower than convection = lower temperature<br>\n – Complete combustion because soot particles don’t rise away = more time to burn<br>\n – Flame appears dim blue because no incandescent soot particles\n <\/div>\n <\/div>\n <\/div>\n\n \n <div class=\"question-card\">\n <div class=\"question-number\">Question 10<\/div>\n <div class=\"question-text\">A car engine produces different exhaust compositions at different speeds. Explain the combustion chemistry behind these variations and identify the most environmentally friendly condition.<\/div>\n <button class=\"toggle-answer\">Show Answer <span class=\"flame-icon\">\ud83d\udd25<\/span><\/button>\n <div class=\"answer-content\">\n <div class=\"answer-text\">\n <strong>Idle Speed (Rich Mixture):<\/strong><br>\n – Fuel-air ratio: Excess fuel, limited oxygen<br>\n – Chemistry: C\u2088H\u2081\u2088 + 8.5O\u2082 \u2192 8CO + 9H\u2082O (incomplete)<br>\n – Results: High CO, unburnt hydrocarbons, soot<br><br>\n <strong>Optimal Speed (Stoichiometric):<\/strong><br>\n – Perfect fuel-air ratio (1:14.7 for petrol)<br>\n – Chemistry: C\u2088H\u2081\u2088 + 12.5O\u2082 \u2192 8CO\u2082 + 9H\u2082O (complete)<br>\n – Results: Maximum efficiency, minimal pollution<br><br>\n <strong>High Speed (Lean Mixture + High Temperature):<\/strong><br>\n – Excess air, high compression temperature<br>\n – Chemistry: N\u2082 + O\u2082 \u2192 2NO (at >1300\u00b0C)<br>\n – Results: Nitrogen oxides formation<br><br>\n <strong>Environmental Recommendation:<\/strong> Optimal speed is most eco-friendly due to complete combustion and minimal harmful emissions.\n <\/div>\n <\/div>\n <\/div>\n\n \n \n\n <\/div>\n\n <div class=\"footer\">\n <p>Class 8 Science – Combustion and Flame | Interactive Questions<\/p>\n <p style=\"margin-top: 10px;\">\ud83d\udd25 Click to reveal answers \ud83d\udd25<\/p>\n <\/div>\n <\/div>\n\n <script>\n document.addEventListener('DOMContentLoaded', function() {\n const toggleButtons = document.querySelectorAll('.toggle-answer');\n \n toggleButtons.forEach(button => {\n button.addEventListener('click', function() {\n const answerContent = this.nextElementSibling;\n const isShowing = answerContent.classList.contains('show');\n \n \/\/ Close all other answers\n document.querySelectorAll('.answer-content').forEach(content => {\n content.classList.remove('show');\n });\n \n document.querySelectorAll('.toggle-answer').forEach(btn => {\n 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test-badge\">Assessment Test<\/div>\n <h3 class=\"card-title\">Combustion and Flame Quiz<\/h3>\n <p class=\"card-description\">Test your understanding of combustion processes, types of flames, and fire safety principles with this comprehensive quiz.<\/p>\n <div class=\"card-features\">\n <div class=\"feature\">\n <span class=\"feature-icon\">\u2705<\/span>\n <span>Multiple choice questions<\/span>\n <\/div>\n <div class=\"feature\">\n <span class=\"feature-icon\">\u23f1\ufe0f<\/span>\n <span>Timed assessment<\/span>\n <\/div>\n <div class=\"feature\">\n <span class=\"feature-icon\">\ud83d\udcca<\/span>\n <span>Instant results<\/span>\n <\/div>\n <\/div>\n <a href=\"https:\/\/m.gyankatta.org\/mod\/quiz\/view.php?id=1574\" class=\"card-button quiz-button\">\n Start Quiz\n <span class=\"button-arrow\">\u2192<\/span>\n <\/a>\n <\/div>\n <\/div>\n \n <div class=\"test-card interactive-card\">\n <div class=\"card-glow\"><\/div>\n <div class=\"card-icon\">\ud83c\udfae<\/div>\n <div class=\"card-content\">\n <div class=\"card-badge interactive-badge\">Interactive Lesson<\/div>\n <h3 class=\"card-title\">Interactive Learning<\/h3>\n <p class=\"card-description\">Engage with dynamic content, animations, and interactive elements that make learning about combustion fun and memorable.<\/p>\n <div class=\"card-features\">\n <div class=\"feature\">\n <span class=\"feature-icon\">\u2728<\/span>\n <span>Animated content<\/span>\n <\/div>\n <div class=\"feature\">\n <span class=\"feature-icon\">\ud83d\uddb1\ufe0f<\/span>\n <span>Interactive elements<\/span>\n <\/div>\n <div class=\"feature\">\n <span class=\"feature-icon\">\ud83c\udfaf<\/span>\n <span>Step-by-step learning<\/span>\n <\/div>\n <\/div>\n <a href=\"https:\/\/m.gyankatta.org\/auth\/mnet\/jump.php?hostid=9&wantsurl=\/mod\/lesson\/view.php?id=95\" class=\"card-button interactive-button\">\n Start Lesson\n <span class=\"button-arrow\">\u2192<\/span>\n <\/a>\n <\/div>\n <\/div>\n <\/div>\n \n <div class=\"learning-objectives\">\n <h3>What You’ll Learn<\/h3>\n <div class=\"objectives-grid\">\n <div class=\"objective\">\n <div class=\"objective-icon\">\ud83d\udd25<\/div>\n <h4>Combustion Process<\/h4>\n <p>Understand how substances burn and the science behind flames<\/p>\n <\/div>\n <div class=\"objective\">\n <div class=\"objective-icon\">\ud83d\ude92<\/div>\n <h4>Fire Safety<\/h4>\n <p>Learn essential fire prevention and safety measures<\/p>\n <\/div>\n <div class=\"objective\">\n <div class=\"objective-icon\">\ud83d\udca1<\/div>\n <h4>Types of Flames<\/h4>\n <p>Explore different flame types and their characteristics<\/p>\n <\/div>\n <div class=\"objective\">\n <div class=\"objective-icon\">\ud83c\udf21\ufe0f<\/div>\n <h4>Temperature Effects<\/h4>\n <p>Study how temperature affects combustion<\/p>\n <\/div>\n <\/div>\n <\/div>\n \n <div class=\"action-section\">\n <div class=\"more-resources\">\n <div class=\"resources-content\">\n <h4>Want More Learning Resources?<\/h4>\n 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0.9);\n font-size: 1.1rem;\n}\n\n\/* Responsive Design *\/\n@media (max-width: 768px) {\n .science-container {\n padding: 20px 15px;\n }\n \n .science-title {\n font-size: 2.5rem;\n }\n \n .tests-wrapper {\n grid-template-columns: 1fr;\n }\n \n .action-section {\n grid-template-columns: 1fr;\n gap: 20px;\n }\n \n .objectives-grid {\n grid-template-columns: 1fr;\n }\n \n .topic-badge {\n font-size: 1.2rem;\n padding: 12px 30px;\n }\n \n .science-hero h2 {\n font-size: 2rem;\n }\n}\n\n@media (max-width: 480px) {\n .science-title {\n font-size: 2rem;\n }\n \n .topic-badge {\n font-size: 1.1rem;\n padding: 10px 25px;\n }\n \n .science-hero {\n padding: 30px 20px;\n }\n \n .science-hero h2 {\n font-size: 1.8rem;\n }\n \n .card-content {\n padding: 0 20px 20px;\n }\n \n .learning-objectives {\n padding: 30px 20px;\n }\n}\n<\/style>\n","protected":false},"excerpt":{"rendered":"<p>Combustion and Flame – Interactive Questions \ud83d\udd25 Combustion & Flame \ud83d\udd25 Class 8 Science – Interactive Conceptual Questions Click on “Show Answer” to reveal detailed explanations Question 1 A student conducted an experiment with three candles of identical size placed in different conditions. Candle A burned for 25 minutes, Candle B for 2 minutes, and […]<\/p>\n","protected":false},"author":1,"featured_media":162789,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"fifu_image_url":"https:\/\/manishchandra.org\/doc\/webtext\/energetics\/CE-images\/candle_flame.jpg","fifu_image_alt":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-162785","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized","cat-1-id","has_thumb"],"yoast_head":"\n<title>Class 8 Science: Combustion and Flame Questions - Gyankatta<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/news.gyankatta.org\/?p=162785\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Class 8 Science: Combustion and Flame Questions - Gyankatta\" \/>\n<meta property=\"og:description\" content=\"Combustion and Flame – Interactive Questions \ud83d\udd25 Combustion & Flame \ud83d\udd25 Class 8 Science – Interactive Conceptual Questions Click on “Show Answer” to reveal detailed explanations Question 1 A student conducted an experiment with three candles of identical size placed in different conditions. 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