American Chemical Society (ACS) Laboratory Safety Practice Test

Water-reactive chemicals are known for their ability to interact with water, leading to the release of toxic gases or other hazardous reactions. These substances can include various metals and nonmetals that undergo vigorous reactions when they come into contact with water, often producing flammable or toxic gases as a byproduct. For instance, alkali metals like sodium and potassium will react with water to release hydrogen gas, which is flammable and can pose a serious risk in laboratory settings.

In contrast, acids generally dissociate in water but do not typically produce toxic gases. Air-reactive chemicals may react with components of the air, but that interaction is different from the specific reactivity with water leading to gas release. Lastly, non-reactive substances are stable and do not engage in chemical reactions, making them safe in the context of water interactions. Therefore, the focus on water-reactive chemicals clearly underscores their potential to cause hazardous situations and is the correct response to the question posed.