To weld metals together, high temperature is required. Such a high tem

To weld metals together, high temperature is required. Such a high temperature is obtained by burning:

Acetylene in oxygen
LPG in oxygen
Methane in oxygen
Acetylene in nitrogen
This question was previously asked in
UPSC NDA-2 – 2015
The correct option is A, Acetylene in oxygen.
Welding requires a high-temperature flame to melt and fuse metals. The combustion of acetylene (C₂H₂) with oxygen (O₂) produces an oxy-acetylene flame, which can reach temperatures of around 3500 °C, making it suitable for welding. Other fuel gases like LPG and methane produce lower temperatures when burned with oxygen. Burning acetylene in nitrogen would not sustain combustion as nitrogen is inert and would not provide the necessary oxidant.
Oxy-acetylene welding is a common process used for welding, cutting, and heating metals. The high temperature is achieved by using pure oxygen as the oxidant instead of air, which contains about 78% nitrogen and would limit the flame temperature. Different ratios of acetylene to oxygen can produce oxidizing, neutral, or carburizing flames, used for various applications.