MCQ Detailed View

Welding is a process used to join metals by melting them together. One of the most common methods is gas welding, which relies on a flame created by combining oxygen and acetylene.

Oxygen is used to support the combustion of acetylene, producing a very hot flame. This flame can reach temperatures up to 3,500 °C, which is sufficient to melt metals like steel. Acetylene, a hydrocarbon gas, burns efficiently with oxygen and allows welders to control the flame precisely for cutting, shaping, or joining metals.

Together, oxygen and acetylene form the oxy-acetylene flame, which is widely used in industries, workshops, and metal fabrication. This method does not typically require additional inert gases like argon, unless performing specialized welding such as TIG welding, which is less common for general welding applications.

Other gases like hydrogen or nitrogen are used in very specific welding techniques but are not standard for most welding processes. Similarly, argon is primarily used as a shielding gas in arc welding, not in the basic gas welding setup.

The principle behind welding with oxygen and acetylene is simple: oxygen intensifies the burning of acetylene, generating high temperatures, and the flame melts the metal. Once the molten metal cools, it fuses the pieces together to form a strong joint. Safety precautions are essential because both gases are flammable and pressurized.

In conclusion, the main gases used in standard welding processes are oxygen and acetylene, making Option 4 the correct answer. Understanding these gases helps students link chemical reactions, combustion, and industrial applications of chemistry.