NEBOSH Practice Test

Hydrogen Sulphide (H2S) is best described by the characteristics of having a pungent smell and being flammable. This gas is known for its distinct rotten egg odor, making it easily identifiable at low concentrations. The presence of hydrogen sulfide can indicate potential hazards, as high concentrations are toxic. Additionally, hydrogen sulfide is flammable, which poses a significant risk in environments where it may accumulate, particularly in confined spaces or areas where there are ignition sources.

The other phrases do not accurately capture the key characteristics of hydrogen sulfide. For instance, while it is true that H2S can be colorless, it is definitely not odorless, nor is it non-toxic; in fact, it is highly toxic at certain levels. The description of being sweet tasting and light is also misleading, as it is not sweet and certainly has a strong and offensive odor rather than a pleasant taste. These details are critical for identifying and managing the risks associated with hydrogen sulfide in various work environments.