Question

how can we test the presence of both oxygen and hydrogen gas by bringing a burning candle close to it

Answer 1

Answer:

A lighted wooden splint makes a popping sound in a test tube of hydrogen. Characteristic test for hydrogen (H2) gas can be performed by bringing a burning candle near the source of hydrogen. On doing so, hydrogen gas burns with a squeaky pop sound. Hydrogen gas is recognised by the 'pop' when it burns.

Answer 2

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Burning splint test

A splint is lit and held near the opening of the tube, then the stopper is removed to expose the splint to the gas. If the gas is flammable, the mixture ignites. This test is most commonly used to identify hydrogen, which extinguishes with a distinctive 'squeaky pop' sound