Question

explain by an experiment that air (oxygen) is necessary for combustion

Answer 1

Take a burning candle and cover the burning candle with a glass jar so that the candle is in an air tight room.
After some time the candles dims and goes out. This shows that air (oxygen) is necessary for combustion.

Answer 2

Aim:

To show that oxygen (air) is necessary for combustion.

Materials Required:

Two candles, a match box and a glass jar. Theory Combustion is a chemical reaction in which a combustible substance burns in air (oxygen) to produce Carbon dioxide , water and heat.

Combustible substance (Fuel) + 0,— CO, + Water + Heat

Procedure:

(i) Light two candles and fix them on the table.

(ii) Cover one of the candles by an inverted glass jar.

Observations:

Candle covered by glass jar extinguishes due to the absence of air while the other candle keeps on burning because it is getting regular supply of oxygen (air). Conclusion Oxygen (air) is necessary for the combustion process.