Which one of the following is known as 'water gas' ?

Water gas is a fuel gas mixture primarily composed of carbon monoxide (CO) and hydrogen (H2). It is industrially produced by passing steam over red-hot carbonaceous fuels like coke or coal at high temperatures, typically around 1270K [2]. The chemical reaction is represented as C + H2O → CO + H2 [2]. While the term 'synthesis gas' or 'syngas' is often used for any mixture of CO and H2, the specific 1:1 ratio produced from steam and coke is traditionally referred to as water gas. This mixture is highly significant in industrial chemistry, particularly for the production of pure hydrogen through the water-gas shift reaction, where CO is further reacted with steam to produce CO2 and additional H2 [4]. Other options like NH3 (ammonia) or H2 + N2 (producer gas components) do not constitute water gas.

Sources

1. [2] https://www.energy.gov/eere/fuelcells/hydrogen-production-natural-gas-reforming
2. [1] https://www.sciencedirect.com/topics/engineering/water-gas-reaction
3. [4] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.1 BONDING IN CARBON – THE COVALENT BOND > p. 60