Texas Commission on Environmental Quality (TCEQ). Class C Water License Exam

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Prepare for the Texas Commission on Environmental Quality (TCEQ) Class C Water License Exam. Utilize flashcards, multiple choice questions, and in-depth explanations. Equip yourself with the skills to succeed!

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Which of the following is a common gas found in water?

  1. Oxygen

  2. Hydrogen sulfide

  3. Helium

  4. Argon

The correct answer is: Hydrogen sulfide

Hydrogen sulfide is a common gas found in water, particularly in ground and surface waters that are impacted by organic decomposition and microbial activity. It is often a byproduct of the anaerobic breakdown of organic matter in the absence of oxygen. This gas is known for its characteristic smell of rotten eggs and can be a concern in water treatment because of its potential to corrode infrastructure and create safety hazards at high concentrations. While oxygen is also found in water, its role is primarily in supporting aquatic life rather than being recognized primarily as a common gas that exists as a dissolved gas under certain conditions. Helium and argon, while present in trace amounts in water, are not commonly associated with typical water quality issues or processes like hydrogen sulfide. Therefore, hydrogen sulfide stands out as a significant and commonly encountered gas in both natural and treated water sources.