Oxygen Therapy

Central piped oxygen: oxygen is distributed via copper pipes circulating from a central source, that is situated outside the building. The source may be liquid oxygen, high-pressure gaseous oxygen cylinders, a large oxygen concentrator or a combination. It has the advantage of reduced risk of fire and obviates handling and transporting heavy cylinders between hospital wards. The high installment and maintenance cost is it's daunting factor.

My fish keeps floating to the top for oxygen or something?

do have water pump? i think u should get one it will make them better and supply more oxygen

Is it just a lucky coincidence that we live on a planet where the gravitational field is strong enough to hold the oxygen but weak enough that we are able to achieve an escape velocity?

There are a lot of exceptional responses here so I wo not repeat what has been stated eloquently already.However, it can be summed up by considering the ancient Greek principle of teleology. Simply put, teleology would state that "a dog has four legs so that it can move". That same statement non-teleologically would be "a dog has four legs and it uses them to move."Life in the universe may have millions of variations that we can barely imagine. there may be a seemingly endless array of lifeform "seeds" floating around out there. Earth may have been bombarded by millions of these. Only one (that we now of) seems to have been able to survive and thrive here.Non-teleologically then of all the types of life in the universe, this one works for us. I suppose you could call that coincidence.About escape velocity: consider that many astronauts are demonstrating a remarkable ability to adapt to weightlessness. Oddly, only species that appeared after the age of dinosaurs have this capability. The questions this generates are tantalizing. For instance, how is it possible to adapt to an environment to which we had not been exposed? It would take many hundreds of generations in weightlessness for a species to develop genetic variations to allow it to adapt.The implications are staggering. A logical conclusion is that those non-saurian species around today must have been derived from genetic material elsewhere in the universe. Even if you accept that, how did that prior species develop weightless adaptability? Are there species out there that have been living for thousands of generations in weightlessness?Equally staggering is if we are not derived from a species that lived continuously in weightlessness, then are we a product of yet another species that manipulated genes that would lie dormant until serendipity caused this whole process to eventually produce a species that can survive in space?Achieve escape velocity? It's on the horizon...so to speak

How Can hydrogen and oxygen be separated from water, so hydrogen can be used as a fuel?

Electrolysis. The only problem is that it takes more energy to do the separation than you get from the combining. So basically it's a waste of time.

If oxygen is 46%ish of earth's crust, how come earth's crust is not a gas?

Because it's locked up in chemical compounds, not in it's elemental form. Same reason that water is not a gas (under normal conditions) even though it's H20 which means it's two thirds hydrogen, one third oxygen.

calculate the mass of the oxygen that reacts with 124grams O methane (natural gas) to form 3.41g of carbon?

nicely for each a million mole of CH4 that reacts, a million mole of CO2 is formed. So divide one gram via CH4's molar mass (16g) to get the type of moles of CH4 you have. Then multiply the type of moles via CO2's molar mass (34g).

Which one of these metals Cu, Mg, Sn and Zn would you expect to be the most reactive towards oxygen?

The enthalpy of formation of Al2O3 is via some distance the main destructive (exothermic) so in reaction to this Al may be the main reactive in the direction of oxygen. Al is even though passivated via the formation of a skinny (yet reliable) oxide layer on its floor

Why does blood turn brown when exposed to oxygen?

Blood turns brown only when it start to decompose, not when is exposed to oxygen. You really have to destroy the hemoglobin molecule before you see the brown pigment. The brown pigment is not iron oxide. It stays in solution after centrifugation. I handle blood samples from every species of animals daily. Some field samples are brown and smelly.