Combustion and Flame

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PYQ MCQs

1 · Learning Hub 2 · Objective (20 MCQs) 3 · Subjective (2/3/5M) 4 · AI Tutor

Faculty Video Lectures

Combustion: Definition, Conditions & Types

10:0396.4 MB stream Slides — Combustion Basics

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Uploaded by Ms. Anita Sharma (Faculty) · Faculty lecture

Flame Zones: The Copper Wire Loop Experiment

10:53169.8 MB stream Slides — Flame Zones Lab

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Uploaded by Ms. Anita Sharma (Faculty) · Faculty lecture

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Verified Quick Summary for Exams

Faculty Verifiedrank score 37.7

by Anita SharmaFacultyText

Exam-ready summary (verified by faculty).

• Combustion: a substance reacts with oxygen giving heat & light. Products: oxides + heat.
• Ignition temperature: minimum temperature for a substance to catch fire. Lower it → easier ignition (matchstick, kerosene ~250°C… use a lamp!)
• Spontaneous combustion happens without heating — white phosphorus (stored under water for safety).
• Fire safety: cut the air (lid/CO₂), never use water on oil or electrical fires.
• Hydrogen = cleanest fuel: 2H₂ + O₂ → 2H₂O, no pollutant.

Tip: in diagrams, always label the blue outer zone as the hottest.

One-Page Revision Notes — Combustion & Flame

rank score 7.7

by Aarav PatelText

COMBUSTION — fast reaction with O₂ → heat + light.

Conditions (Fire Triangle):
1. Combustible substance (fuel)
2. Oxygen / air
3. Temperature = ignition temperature

Types: Slow (respiration) · Rapid (matchstick) · Spontaneous (white P) · Smouldering (no air)

Flame zones (candle):
• Innermost — dark, unburnt vapours
• Luminous — yellow, glowing carbon (soot here!)
• Outermost — blue, complete combustion, HOTTEST

Calorific value = heat from 1 kg complete burn (kJ/kg).
Wood 15–25 · Petrol 48 · Diesel 45 · LPG 50 · H₂ 150 (cleanest!)

Acidic oxides ← non-metals (CO₂, SO₂) | Basic oxides ← metals.

Flame Zones Diagram + Temperature Notes

rank score 4.9

by Diya MehtaText

Draw the teardrop flame and shade three zones:
1. NON-LUMINOUS (darkest) — wax vapours rise here, not yet burnt.
2. LUMINOUS (yellow) — partial burning; unburnt carbon glows. Hold a cold surface here → SOOT deposits (activity: copper wire loop gets blackened!)
3. OUTERMOST (blue) — complete burning, highest temperature.

Observation: copper wire loops — blackens fastest in the luminous zone, melts first in the outer zone.

Why outer is blue: complete combustion + most air supply.

PYQ Bank (CBSE + State Board 2020–2023) with Explanations

rank score 2.8

by Rohan KulkarniText

Collected previous-year MCQs I have solved:

[CBSE 2023] Unit of calorific value → kJ/kg
[CBSE 2022] Hottest zone of candle flame → outermost
[CBSE 2021] Spontaneous combustion example → white phosphorus
[CBSE 2020] Non-metals burn to give → acidic oxides
[State 2022] Smouldering occurs in absence of → air
[Exemplar] Soot is formed in → luminous zone
[State 2023] Petrol, kerosene, diesel come from → crude oil
[CBSE 2023] Lowest calorific value among common fuels → wood

Keep practising the conversion: F = 9/5 C + 32 also appears in combo questions.

Mnemonics — Calorific Values & Oxides

rank score 2.1

by Sneha SinghText

Quick memory aids:

"W-P-D-L-N-H" for ascending calorific value:
Wood → Petrol → Diesel → LPG → Natural gas → Hydrogen (150 kJ/kg, king of clean fuel 👑)

OXIDES rule — "Metals go Basic, Non-metals turn Acidic":
Fe, Na, Mg → basic oxides | C, S, P, N → acidic oxides.

Fire safety — "S-C-C": Switch off, Cover (lid/CO₂), Call for help. NEVER water on oil/electric fires.

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