Question

Hoq can we test the presence of Hydrogen gas?

Answer 1

when we will keep a burning candle near the mouth of testube a popping sound will come and the candle will blow off.

Answer 2

Yes we can test the presence of the Hydrogen gas.
Hydrogen gas burns with a pop sound.
This property can be used to test if the reaction liberates hydrogen or it doesn't.
To test it one can use a matchstick or a candle or any small burning material.
But small only.
Since hydrogen is highly inflammable.