Question

pls tell the foggy gas liberated when aluminium is heated with matchstick

Answer 1

A ‘squeaky pop’ sound will be heard, as you ignite the H2 gas.

The procedure you have described is often used to test for the presence of hydrogen gas. It is informally named ‘the squeaky pop test’. You bring a lit splint to the mouth of a test tube containing suspect gas (the gas which you are testing). The positive result is that you hear the squeaky pop, and thus you have evidence that the suspect gas does indeed contain H2. (A small amount of) water is produced by the combustion reaction which takes place, but you are unlikely to be able to observe this. The equation of the reaction is:

2H2+O2→2H2O

(hydrogen + oxygen → water)