Which of the following is considered a chemical irritant?

Ammonia gas is classified as a chemical irritant due to its ability to cause irritation to the eyes, skin, and respiratory tract. When inhaled, ammonia can lead to symptoms such as coughing, throat irritation, and difficulty breathing. Additionally, exposure to concentrated ammonia can cause severe burns to the eyes and skin. The chemical's corrosive nature contributes to its classification as an irritant, making it important for those handling or being exposed to it in occupational settings to utilize proper safety precautions, such as wearing personal protective equipment and ensuring good ventilation.

In contrast, water is not considered a chemical irritant in general contexts, as it is typically safe for skin contact and ingestion. Carbon dioxide, while it can be harmful in high concentrations due to suffocation risks, does not act as an irritant in the same way ammonia does. Silica dust, although hazardous due to lung disease risks upon inhalation, is typically characterized as a physical hazard rather than a chemical irritant.