ANS:D - all (a), (b) and (c)

Steam Reforming of Naphtha and Cracking of Natural Gas: This method involves two primary processes:

1. • Steam Reforming of Naphtha: Naphtha, a hydrocarbon mixture, is reacted with steam (water vapor) in the presence of a catalyst at high temperatures (typically 700-1000°C) to produce hydrogen gas (𝐻2H2​) and carbon monoxide (𝐶𝑂CO) according to the following reaction: 𝐶𝐻4+𝐻2𝑂→𝐶𝑂+3𝐻2CH4​+H2​O→CO+3H2​
   • Cracking of Natural Gas (Steam Methane Reforming): Natural gas, primarily composed of methane (𝐶𝐻4CH4​), is reacted with steam under similar conditions to produce hydrogen gas and carbon monoxide: 𝐶𝐻4+𝐻2𝑂→𝐶𝑂+3𝐻2CH4​+H2​O→CO+3H2​ These processes are carried out in large-scale industrial facilities and are the most common methods for commercial hydrogen production due to the abundance and relatively low cost of natural gas and naphtha.
2. Electrolysis of Water: Electrolysis of water involves passing an electric current through water to split it into hydrogen gas and oxygen gas. This process occurs in an electrolysis cell equipped with electrodes and an electrolyte solution. The electrical energy breaks the water molecules apart into hydrogen and oxygen atoms: 2𝐻2𝑂(𝑙)→2𝐻2(𝑔)+𝑂2(𝑔)2H2​O(l)→2H2​(g)+O2​(g) While electrolysis of water offers a clean and sustainable method for hydrogen production using renewable energy sources, such as solar or wind power, it is currently less common for large-scale commercial hydrogen production due to higher energy costs compared to steam reforming.
3. Cryogenic Separation of Hydrogen from Coke Oven Gas: Coke oven gas is a byproduct of the coking process used in steelmaking, and it contains hydrogen along with other gases like methane and carbon monoxide. Cryogenic separation involves cooling the gas mixture to very low temperatures (-253°C) to liquefy hydrogen while leaving the other gases in gaseous form. The liquefied hydrogen is then separated and purified. While this method can be used for hydrogen production, it is less common than steam reforming for large-scale commercial applications due to the specific source of coke oven gas and the energy-intensive nature of cryogenic separation.

Therefore, while all three methods can be used for hydrogen production, steam reforming of natural gas and naphtha is the most widely used and economically feasible method for commercial production of hydrogen for the manufacture of nitrogenous fertilizers.