In normal usage in an oxy/acetylene cutting torch, the acetylene hose is red and the oxygen hose is green.
Red for the combustible gas (Acetylene - MAPP - Propane), green for the Oxygen. All Oxy-fuel torches use these hose colors.
red
As far as I am aware. The gauges themselves are the same. Usually brass. Unless someone has painted them. The hoses on the other hand are red and green. The red being for the acetylene. A lot of times the tanks will be painted the same way although I have seen some acetylene tanks painted black.
Oxygen and acetylene hose fittings are made with different screws to prevent connecting the wrong gas to the hoses.
Oxygen tank, Acetylene tank, regulators for each tank, hoses, a torch, and a striker. Check valves are also a good idea if they're not already installed.
Red.
They aren't, which is why you should never have them laying near your work area. What I do is drape them over my shoulder and keep them behind me.
no
Acetylene is a covalent compound
Acetylene is a neutral compound.
Acetylene has a linear molecule.
Acetylene, C2H2, is a pretty simple hydrocarbon. http://en.wikipedia.org/wiki/Acetylene