Class 8 Practice – Level 2 – Set 1 – Combustion and Flame

Total questions: 25

Which of the following is an example of explosion combustion?

Burning of coal in a furnace

Lighting a matchstick

Explosion of a firecracker

Burning of LPG in a stove

None

In a Bunsen burner, which flame is the most efficient for heating purposes?

Luminous yellow flame

Bright yellow flame

Non-luminous blue flame

Flickering orange flame

None

Why is carbon dioxide gas used in fire extinguishers?

It increases the temperature of the fire

It is highly flammable

It displaces oxygen and cools the surroundings

It absorbs oxygen from the air

None

What are the main products of combustion when a hydrocarbon fuel like methane (CH₄) burns completely?

Carbon monoxide and hydrogen

Carbon dioxide and water

Nitrogen and oxygen

Hydrogen and oxygen

None

Which gas is primarily responsible for global warming and is released during the combustion of fossil fuels?

Oxygen

Carbon dioxide

Methane

Nitrogen

None

Which of the following fuels has the highest calorific value?

Wood

Coal

Kerosene

LPG

None

Which of the following materials is least likely to catch fire easily due to a high ignition temperature?

Paper

Kerosene

Wood

Iron

None

What should you do if a gas stove catches fire?

Pour water on it

Throw sand on it

Cover the flame with a wet cloth

Switch off the gas supply and cover it with a lid

None

Which of the following is a correct method to break the fire triangle and extinguish a fire?

Increase the fuel supply

Add more oxygen

Cool the fuel below its ignition temperature

Use a fan to provide air

None

10.

Why are foam extinguishers effective against fires caused by flammable liquids?

They remove fuel from the fire

They increase the oxygen supply

They cool the fire and form a blanket over the liquid

They release carbon monoxide

None

11.

The calorific value of a fuel is measured in:

Kilojoules per liter

Kilojoules per kilogram

Joules per second

Kilograms per meter

None

12.

Why is LPG preferred over coal for cooking purposes?

It is cheaper than coal

It produces more smoke

It is cleaner and more efficient

It has a lower calorific value than coal

None

13.

Which of the following is an example of slow combustion?

Burning of paper

Burning of wood

Rusting of iron

Explosion of a bomb

None

14.

How can the spread of a forest fire be effectively controlled?

By adding dry leaves to the fire

By creating fire breaks

By blowing air on the fire

By letting the fire spread naturally

None

15.

What harmful gas is produced during the incomplete combustion of carbon-based fuels?

Nitrogen

Oxygen

Carbon monoxide

Water vapor

None

16.

Which part of a flame undergoes the least combustion?

The blue outer zone

The bright middle zone

The tip of the flame

The dark inner zone

None

17.

Which of the following fuels is considered eco-friendly?

CNG

Diesel

LPG

Coal

None

18.

Which of the following conditions is necessary for spontaneous combustion?

High oxygen levels

High fuel supply

Self-ignition at room temperature

No ignition source

None

19.

Which material will burn with the lowest ignition temperature?

Paper

Glass

Iron

Sand

None

20.

Which of the following fuels produces the least amount of pollutants when burned?

Wood

Petrol

Diesel

Natural gas

None

21.

Which fire extinguisher is best suited for electrical fires?

Water-based extinguisher

Foam-based extinguisher

CO₂-based extinguisher

Sand extinguisher

None

22.

Which of the following processes releases energy?

Photosynthesis

Respiration

Absorption

Diffusion

None

23.

Which of the following should NOT be used to extinguish an electrical fire?

CO₂ extinguisher

Water

Fire blanket

Sand

None

24.

What type of combustion occurs when wood burns slowly in a bonfire?

Explosion combustion

Rapid combustion

Slow combustion

Spontaneous combustion

None

25.

Which safety measure should be taken to avoid fires from flammable gases like LPG?

Store LPG cylinders near the stove

Use a damp cloth near the flame

Ensure proper ventilation and maintenance of gas stoves

Keep the gas cylinder in a closed room

None

1 out of 25

Time's up

Class 8 Practice – Level 2 – Set 1 – Combustion and Flame

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