The oxy/acetylene welding torch is used to ___ the oxygen and acetylene gases in the proper proportioned, and to control the ____ of these gases burned at the tip.

The correct answer highlights the key functions of the oxy/acetylene welding torch, specifically its role in combining oxygen and acetylene gases in a precise manner and regulating the amount of these gases that are burned at the torch tip.

When using the torch, it is crucial to mix the oxygen and acetylene in the right proportions to achieve an optimal flame for welding or brazing. The correct balance ensures that the flame is neither too oxidizing nor too carburizing, which would adversely affect the quality of the weld.

Further, controlling the volume of gases burned at the tip is important because it directly influences the flame characteristics, including its heat output and stability. A higher volume can produce a larger, hotter flame, while a lower volume results in a smaller flame. Proper control allows the welder to adjust the flame to suit the specific materials and thicknesses being joined, ensuring effective heat application without damaging the surrounding material.

This comprehensive understanding emphasizes the functionality of the torch in both mixing and managing gas output, which is essential for successful welding operations.