Acetylene, C2H2, is a pretty simple hydrocarbon. http://en.wikipedia.org/wiki/Acetylene
n - Oxygen and Acetylene are the original gasses that are used for welding/cutting. Newer mixtures are slowly replacing Acetylene as a fuel. These gasses don't always reach the temperatures attained by Acetylene. Us old-timers still prefer Acetylene.
Bioxially oriented Poly proplene
An acetylene or propane torch.
You answered your own question. Oxygen and Acetylene. Other mixes are now used in place of Acetylene so the process is now called Oxy-Fuel.
Acetylene
Red for the combustible gas (Acetylene - MAPP - Propane), green for the Oxygen. All Oxy-fuel torches use these hose colors.
LPG is liquid petroleum gas and oxy-acetylene is oxy fuel welding. The LPG can be used as an alternative to oxy-acetylene and is cheaper and can be purchased in bulk. The oxy-acetylene is best used when making shorter, thinner, and faster cuttings.
Argon is an inert gas- it does not react with any other gasses. While fuel gasses (acetylene) and oxygen must be separated during storage due to the fire hazard, there IS no fire hazard from an inert gas. It may be stored with fuel gasses or with oxygen.
Ethylyne, or the chemical better known as acetylene, C2H2 is not used in automobiles as a fuel source. Some vehicles run on natural gas, a mixture of alkanes, C1-C4. Acetylene is more commonly used in welding applications or as building block to produce larger chemicals.
A general rule is 3 parts Oxygen to 1 part Acetylene. Other fuel gasses may vary the ratio. This produces a Neutral flame. See the answer to "Types of flames" for more info.
Acetylene is a covalent compound
Acetylene is a neutral compound.