To keep it safe!
yes
Oxygen stored as liquid is highly flammable.
Because they find themselves in environments of little or no oxygen, and oxygen is essential to life.
Compressed oxygen--oxygen that is stored as a gas in a tank.
We can compress the hydrogen because hydrogen gas is stored in the cylinders.
Pure Oxygen is stored either as a gas in high pressure gas cylinders or as a liquid in large cryogenic tanks. Highly Flammable. :)
yes
Assuming you're talking about the oxygen cylinders a patient would use at home - then no. The Oxygen is simply stored under high pressure in the cylinder, and is released through the step-down valve.
Blos
You can buy oxygen cylinders online at http://www.trishir.com/products-details.asp?POID=251 They offer many cylinders of small,medium portable cylinders You can buy small oxygen cylinders at www.oxygenmobility.com For more details call 800-716-6674.
Because it would otherwise mix with air, making it impure.
Because it makes them easier to hold
Oxygen stored as liquid is highly flammable.
Compressibility. A lot of gas is forced into the cylinders.
Yes
The simple answer is ... you don't. A majority of scuba dives use compressed air in the cylinders. Therefore you don't need "oxygen" cylinders. HOWEVER, if you are a diver that is diving on Nitrox, in which divers change the amount of oxygen vs nitrogen in their air, then your tank needs to be "oxygen clean" because you are putting oxygen in first, then nitrogen.
the air becomes rarefied and has a very low oxygen