Combustion and flame class 8 science

The lowest temperature at which a substance catches its fire is called

• Moderate temperature

• Ignition temperature

• Minimum temperature

• Extreme temperature

The main constituents of bio gas is-

• Butane

• Methane

• Nitrogen

• Ethane

The types of combustion in which a material suddenly burst into flames is called-

• Rapid combustion

• Explosion

• Spontaneous combustion

• None of these

The----------zone in a candle flame is the zone of no combustion

• Non luminous zone

• Luminous zone

• Dark zone

• None of these

Which is the hottest part in the flame of the candle?

• Blue

• Yellow

• Black

• Wax part

Incomplete combustion gives_____

• Carbon dioxide

• Carbon monoxide

• Carbon

• Oxygen

The quantity of heat produced by a unit mass of a fuel on complete combustion is called-

• Combustion value

• Calorific value

• Common value

• Heat value

Which of the fuel has highest calorific value?

• Wood

• CNG

• LPG

• Petrol

The substances which have very low ignition temperature and can easily catch fire are called

• Flammable substances

• Inflammable substances

• Combustible substances

• Non combustible substance

Which gas in atmosphere is responsible for global warming?

• Carbon monoxide

• Nitrogen oxide

• Carbon dioxide

• Sulphur dioxide