A gas when mixed with oxygen, it produces a very hot and early controllable flame. What is the name of the flame and where is it used?

Analysis

The question asks for the identification of a specific gas mixture that produces a high-temperature, controllable flame, and its practical application in industry.

Concept Explanation

The flame in question is produced by the combustion of ethyne (commonly known as acetylene) in the presence of pure oxygen. When ethyne ($C_2H_2$) burns in oxygen, it produces an extremely high temperature (reaching up to 3000°C). This is known as an oxy-acetylene flame.

Note: In some older or specific curriculum contexts, "oxy-ethylene" is occasionally used interchangeably or erroneously in textbooks, but the chemical process described—a very hot, controllable flame used for metalwork—refers to the oxy-acetylene process.

Step-by-Step Solution

1. Identify the gas: The gas is ethyne ($C_2H_2$). When mixed with oxygen, it undergoes complete combustion to produce a very hot flame.
2. Identify the application: Because this flame produces enough heat to melt steel and iron, it is the standard tool used in welding (joining metals) and cutting (slicing through thick metal plates).
3. Evaluate the options: • Miners' lamps (Options A and C) typically use acetylene, but they are designed to produce light, not the high-intensity heat required for cutting or welding. • The term "Oxy-ethylene" in the options is a common nomenclature variation found in some JAMB question banks for this specific question, referring to the oxy-acetylene process. • Option D correctly identifies the application as "cutting and welding metals," which is the primary industrial use of this flame.

Conclusion

The oxy-acetylene flame is essential in engineering and construction for metal fabrication. While the terminology in the options uses "oxy-ethylene," the functional description of "cutting and welding metals" makes Option D the only scientifically accurate application provided.

Exam Tip: Whenever you see questions about "very hot flames" in Chemistry, immediately think of welding. If the question mentions "miners' lamp," look for the use of acetylene for illumination, not for heat.