Question

Which of the following processes does NOT involve use of dihydrogen?

• A. Gasification of coal
• B. Formation of vanaspati ghee
• C. Preparation of HCl
• D. Preparation of metal hydride lb

Hint:

Coal gasification is a famous commercial production method for generating hydrogen gas on a large scale. Since it acts as a synthesis source for $\text{H}_2$, it does not consume $\text{H}_2$ as a starting material.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks to identify the industrial process that does not require molecular dihydrogen ($\text{H}_2$) as a reactant.

Step 2: Detailed Explanation:
Let's analyze the chemical role of hydrogen in each process:

Gasification of coal: Coal (solid carbon) is reacted with high-temperature steam ($\text{H}_2\text{O}$) to produce syngas, which is a mixture of CO and $\text{H}_2$. This process produces dihydrogen rather than consuming it:
$$ \text{C}_{(s)} + \text{H}_2\text{O}_{(g)} \rightarrow \text{CO}_{(g)} + \text{H}_{2(g)} $$

Formation of vanaspati ghee: Vegetable oils undergo catalytic hydrogenation using $\text{H}_2$ gas in the presence of a nickel catalyst to form saturated fats.

Preparation of HCl: Hydrogen gas directly combines with chlorine gas to produce hydrogen chloride:
$$ \text{H}_{2(g)} + \text{Cl}_{2(g)} \rightarrow 2\text{HCl}_{(g)} $$

Preparation of metal hydride: Highly reactive metals combine with $\text{H}_2$ gas under heat to form ionic or covalent metal hydrides (e.g., $2\text{Na} + \text{H}_2 \rightarrow 2\text{NaH}$).


Step 3: Final Answer: The process that does not involve the use of dihydrogen is gasification of coal, matching option (A).