Quiz on Combustion and Flame

List conditions under which combustion can take place.

• a combustible substance.

• oxygen, that is, the supporter of combustion.

• attainment of ignition temperature of the substance.

Explain how the use of CNG in automobiles has reduced pollution in our cities.

• It gives out less carbon dioxide gas, carbon monoxide gas, sulphur dioxide and nitrogen dioxide.

• It leaves behind no residue after its combustion.

Compare LPG and wood as fuels.

• It does not cause pollution on combustion.

• No smoke is produced.

• It can be easily transported, as it is stored in cylinders.

• It is a liquid fuel.

• It has more calorific value (55000 kJ/kg).

Give reasons. (a) Water is not used to control fires involving electrical equipment. (b) LPG is a better domestic fuel than wood. (c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.

Make a labelled diagram of a candle flame.

Name the unit in which the calorific value of a fuel is expressed.

Explain how CO2 is able to control fires.

It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.

Which zone of a flame does a goldsmith use for melting gold and silver and why?

In an experiment, 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.