What is commonly referred to as an acid testing gas?

The term "acid testing gas" is usually associated with carbon dioxide. In many geological and industrial contexts, carbon dioxide is utilized to assess the presence of acids due to its capacity to react with basic substances. This reaction can help determine the acidity of a solution or geological formation by indicating whether certain minerals or compounds are present.

While carbon monoxide and the other gases listed may have their own chemical significance, they do not play a role as "acid testing" gases in the way that carbon dioxide does. For instance, hydrogen sulfide is known for its toxicity and specific industrial applications but does not serve a prominent role in indicating acidity. Similarly, nitrogen oxides and hydrogen sulfide are more relevant in discussions around pollution and industrial processes rather than acid-base reactions.

Understanding the role of carbon dioxide in testing and assessing gas and mineral reactions provides insight into various industrial and environmental processes, making it a critical component in geochemical evaluations and other related fields.