Q. Consider the following matches:

1. Compressed Natural Gas (CNG) → Methane
2. Coal Gas → Hydrogen
3. Liquefied Petroleum Gas (LPG) → Propane and Butane
4. Water Gas → Carbon monoxide and Hydrogen

How many of the above matches are correct?
Answer: Only 1, 3 and 4
Notes: CNG primarily contains methane. LPG consists of propane and butane. Water gas is a mixture of carbon monoxide and hydrogen. However, coal gas mainly comprises hydrogen, methane, and carbon monoxide—so labelling it solely as hydrogen is inaccurate. Thus, only statements 1, 3, and 4 are completely correct.