Which of the following is not true about hydrogen sulfide?

Hydrogen sulfide is indeed known for its characteristic rotten egg smell, which is a defining trait of the gas that can be detected even at very low concentrations. In terms of its physical properties, hydrogen sulfide is heavier than air; it has a density of around 1.4 times that of air, which means it will tend to accumulate in low-lying areas rather than dissipating into the atmosphere.

Furthermore, hydrogen sulfide is flammable and can be explosive when present in certain concentrations within air. This poses a significant risk in environments where it is generated or where wastewater treatment processes take place.

Given that hydrogen sulfide is heavier than air, stating that it is lighter than air is incorrect. This distinction is critical for safety protocols and operational understanding in wastewater treatment facilities, where the management of gases like hydrogen sulfide is a necessary consideration.