Question

How is hydrogen gas collected? Why? ​

Answer 1

Explanation:

Hydrogen is collected by downward displacement of water as it is less denser than water. Hence it comes out at the surface of water . It is insoluble in water so it does not dissolve in water. In case of displacement with air, it is not possible even if hydrogen is lighter than air (14.5 times lighter than air).

Answer 2

Hydrogen is collected after air undergoes fractional distillation and all the gases present in air.