Which of the following describes the soap-box test's detection of leaks?

The soap-box test is a method commonly used to detect leaks, particularly in systems containing gases, such as landfill gas collection systems. When soap solution is applied to a potential leak site, the presence of bubbles indicates that gas is escaping from the system. The formation of bubbles is a clear visual indicator, making it easy to determine where leaks may be occurring.

This methodology relies on the principle that gas escaping through a small orifice will entrain the soap solution, leading to the production of bubbles. Therefore, if bubbles are present, it confirms the existence of a leak at that point. This makes the first option accurate because it directly describes the operational principle of the soap-box test in leak detection.

The other options do not accurately describe the soap-box test. For example, changes in color or sounds are not associated with this method, nor is temperature drop a standard indicator for detecting gas leaks using soap solutions.