Which of the following gases is NOT present in MAPP gas?

MAPP gas, which stands for Methylacetylene-Propadiene Propane, is a fuel gas that primarily consists of a mixture of methylacetylene and propadiene. It is specifically designed for use in welding, cutting, and brazing applications due to its higher flame temperature compared to other fuels like acetylene.

Oxygen is not a component of MAPP gas itself; rather, it is used as an oxidizer in combination with MAPP gas during combustion processes. The role of oxygen in welding or cutting operations is to enhance the combustion of the fuel gas, resulting in a hotter flame, but it is not a constituent of the gas mixture. Therefore, oxygen's absence within the composition of MAPP gas makes it the correct answer to the question regarding which gas is not a part of MAPP gas.

In contrast, propadiene, butadiene, and methylacetylene are all components of the MAPP gas formulation, contributing to its chemical properties and effectiveness as a fuel gas in various applications.