What is combustion?
A.A physical process of melting
B.A chemical process in which a substance reacts with oxygen to give off heat
C.A process of cooling substances
D.A process of mixing substances
What are the three essential requirements for combustion?
A.Fuel, water, and heat
B.Fuel, air (oxygen), and heat
C.Fuel, carbon dioxide, and heat
D.Fuel, nitrogen, and light
What is ignition temperature?
A.The temperature at which a substance melts
B.The temperature at which a substance boils
C.The lowest temperature at which a substance catches fire
D.The highest temperature a substance can reach
Why doesn't a paper cup with water burn when heated?
A.Paper is not combustible
B.Water prevents oxygen from reaching the paper
C.Heat is absorbed by water, keeping paper below its ignition temperature
D.Water makes paper non-flammable
Which of the following is an inflammable substance?
A.Water
B.Stone
C.Petrol
D.Iron
Why is water not suitable for extinguishing electrical fires?
A.Water is too heavy
B.Water may conduct electricity and harm people trying to douse the fire
C.Water makes electrical fires worse
D.Water evaporates too quickly
How does carbon dioxide help in controlling fires?
A.It cools down the fire
B.It is heavier than oxygen and covers fire like a blanket, cutting off oxygen supply
C.It reacts with fuel to stop burning
D.It absorbs heat from the fire
What type of combustion occurs when gas burns on a stove?
A.Spontaneous combustion
B.Rapid combustion
C.Explosion
D.Slow combustion
What is spontaneous combustion?
A.Combustion that requires a matchstick
B.Combustion in which material suddenly bursts into flames without any apparent external cause
C.Combustion that produces a lot of smoke
D.Combustion that occurs under water
Which zone of a candle flame is the hottest?
A.Dark innermost zone
B.Yellow luminous zone
C.Blue outermost zone
D.All zones have same temperature
Why do substances that vaporize during burning produce flames?
A.Vapors are always hot
B.Vapors can burn in gaseous form, producing visible flame
C.Vapors are lighter than air
D.Vapors contain more oxygen
What does the black deposit on a glass plate held in the yellow zone of a flame indicate?
A.Complete combustion
B.Presence of unburnt carbon particles
C.Presence of oxygen
D.High temperature
What is calorific value?
A.The temperature at which fuel burns
B.The amount of heat energy produced on complete combustion of 1 kg of fuel
C.The time taken for fuel to burn completely
D.The amount of smoke produced by fuel
Which fuel has the highest calorific value?
A.Coal
B.Wood
C.Hydrogen
D.LPG
What is the main cause of global warming related to combustion?
A.Production of water vapor
B.Production of carbon dioxide
C.Production of nitrogen
D.Production of heat
What is acid rain and how is it formed?
A.Rain mixed with acids from laboratories
B.Rain that becomes acidic when oxides of sulfur and nitrogen dissolve in it
C.Rain that falls in acidic regions
D.Rain that is naturally acidic
Why is carbon monoxide dangerous?
A.It causes acid rain
B.It is a very poisonous gas produced by incomplete combustion
C.It causes global warming
D.It is flammable
Why is CNG considered a cleaner fuel?
A.It is cheaper than petrol
B.It produces harmful products in very small amounts
C.It burns faster than other fuels
D.It has a pleasant smell
What safety precaution should be taken when burning coal in a room?
A.Keep windows closed
B.Never burn coal in a closed room due to carbon monoxide production
C.Use only small amounts of coal
D.Keep a bucket of water nearby
What happens when a burning cloth is covered with a blanket?
A.Fire spreads to the blanket
B.Fire is extinguished by cutting off oxygen supply
C.Fire burns more intensely
D.Blanket catches fire immediately
Which part of the matchstick contains white phosphorus in old-style matches?
A.The wooden stick
B.The head of the match
C.The striking surface
D.White phosphorus was never used
Why do modern safety matches use red phosphorus instead of white phosphorus?
A.Red phosphorus is cheaper
B.Red phosphorus is much less dangerous than white phosphorus
C.Red phosphorus burns better
D.Red phosphorus is more available
What causes the explosion in firecrackers?
A.Slow release of gases
B.Sudden reaction producing heat, light, sound and large amount of gas
C.Chemical mixing
D.Heat production only
Why doesn't charcoal produce a flame when it burns?
A.Charcoal doesn't burn properly
B.Charcoal does not vaporize during burning
C.Charcoal burns too slowly
D.Charcoal doesn't get hot enough
What makes LPG a good domestic fuel?
A.It is the cheapest fuel
B.It burns easily, has high calorific value, and is easy to control
C.It is available everywhere
D.It never runs out
What happens to polar ice caps due to global warming?
A.They become thicker
B.They melt, causing rise in sea level and coastal flooding
C.They move to different locations
D.Nothing significant happens
Why do we get unburnt carbon particles in incomplete combustion?
A.There is too much fuel
B.There is insufficient oxygen for complete burning
C.Temperature is too low
D.Fuel is of poor quality
How does deforestation relate to fuel use?
A.Cutting trees for wood fuel leads to deforestation
B.Deforestation has no relation to fuels
C.Deforestation produces more fuel
D.Trees grow back immediately
What is the advantage of using a glass tube in the dark zone of a flame?
A.It cools the flame
B.It proves that unburnt vapors are present in the dark zone
C.It makes the flame brighter
D.It increases the flame temperature
Why is hydrogen considered an excellent fuel despite safety concerns?
A.It is very cheap
B.It has extremely high calorific value (150,000 kJ/kg)
C.It is available everywhere
D.It burns very slowly
What precaution should be taken while leaving a forest after a picnic?
A.Take all garbage with you
B.Completely extinguish all campfires
C.Plant new trees
D.Feed the animals
What is the role of air/oxygen in the fire triangle?
A.It provides fuel for burning
B.It supports combustion by reacting with fuel
C.It cools down the fire
D.It provides light to the fire
How does burning fossil fuels contribute to acid rain?
A.Fossil fuels contain acids
B.Burning releases sulfur and nitrogen oxides which form acids in rainwater
C.Fossil fuels make clouds acidic
D.Fossil fuels change the pH of air
Why can't water be used to extinguish oil fires?
A.Water makes oil burn faster
B.Water is heavier than oil and sinks below it, so oil continues burning on top
C.Water and oil react dangerously
D.Water evaporates too quickly
What causes the yellow color in the luminous zone of a flame?
A.Complete combustion
B.Glowing of hot unburnt carbon particles
C.Presence of oxygen
D.High temperature
How do fire extinguishers containing baking soda work?
A.Baking soda cools the fire
B.Baking soda releases CO₂ which cuts off oxygen supply
C.Baking soda absorbs heat
D.Baking soda neutralizes the fire
What makes an ideal fuel?
A.Only high calorific value
B.Readily available, cheap, burns easily, high calorific value, and produces no harmful substances
C.Only being cheap and available
D.Only burning easily
Why do green leaves not burn easily but dry leaves catch fire quickly?
A.Green leaves are non-combustible
B.Green leaves contain moisture which needs to be evaporated first
C.Green leaves have higher ignition temperature
D.Green leaves don't contain carbon
How does the calorific value help in choosing fuels?
A.Higher calorific value means more heat per kg, making fuel more efficient
B.Lower calorific value is always better
C.Calorific value doesn't matter
D.Only the cost matters
What long-term environmental solution can reduce combustion-related pollution?
A.Using more coal
B.Transitioning to renewable energy sources like solar and wind
C.Burning fuels more slowly
D.Using only liquid fuels
Why is understanding combustion important for environmental protection?
A.It helps us burn more efficiently
B.It helps us understand pollution sources and develop cleaner alternatives
C.It makes fuels cheaper
D.It helps us find more fuel