combustion and flame class 8

Which one of the following gases is used in combustion?

• Hydrogen

• Oxygen

• Nitrogen

• Carbon dioxide

The burning of LPG is an example of

• rapid combustion

• spontaneous combustion

• slow combustion

• explosion

Coal is an inflammable fuel.

• True

• False

The _______ zone of a candle flame, is the coldest.

Which of the sentences are correct?

• The outermost part of a candle flame consist unburnt carbon particles.

• All solid fuels have a higher calorific value than liquid and gaseous fuels

• The heat produced by burning completely one kilogram of a given fuel, is known as the efficiency of that fuel.