why can hydrogen be collected?

Answer 1

Hydrogen can be collected through the process of electrolysis which is the breaking apart of water molecules with electricity to form hydrogen and oxygen gas.

Hydrogen gas is a stable molecule so it can be stored easily, however pure Hydrogen, H not H2 is known to be explosive, but it can still be stored in containers similar to any other fuels.

Answer 2

Hydrogen can be collected because it is a gaseous element that is present in combination with other elements in molecules, that can be broken down into the constitutents. I n order to do so, follow these directions: "Ex 2. Method for preparing and collecting a gas less dense (lighter) than air by reacting a liquid and a solid. The less dense gas rises into, and displaces, the more dense air. This is called upward delivery.
e.g. A mixture of zinc and hydrochloric acid makes hydrogen. Hydrogen gives a squeaky pop! with a lit splint. See also methods Ex 5., Ex 6. and Ex 7.

Zn(s) + 2HCl(aq) ==> ZnCl2(aq) + H2(g) "

You would have the set up in a system with a manometer, and cause the gas produced to be able to escape only via the manometer, so you can measure it, and direct it to a single container.

Answer 3

It takes too much energy to collect it. So it's inefficient.