3 - a, 4 - b.Column 1 Column 21. Water gas d. Carbon, Monoxide, Hydrogen2. Natural gasc. Methane, Ethane 3. CNG a. Methane 4. LPGb. Butane and PropaneHence, option 1 is correct. Water Gas:Water-gas is a mixture of CO and H2. However, by-products such as char, tar, soot, ash, and condensates are also produced. Natural gas (also called fossil gas; sometimes just gas), is a naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes, and sometimes a small percentage of carbon dioxide, nitrogen, HYDROGEN sulfide, or helium.Compressed natural gas is a fuel that can be used in place of petrol (gasoline), diesel fuel, and liquefied petroleum gas (LPG).CNG combustion produces FEWER undesirable gases than the aforementioned fuels. In comparison to other fuels, natural gas poses less of a threat in the event of a spill, because it is LIGHTER than air and disperses quickly when released.Liquefied petroleum gas (LPG or LP gas), is a flammable mixture of hydrocarbon gases used as fuel in heating appliances, cooking equipment, and vehicles. It is a mixture of 48% propane, 50% butane, and 2% pentane.