What term describes a chemical that does not dissolve in a liquid?

The term that describes a chemical that does not dissolve in a liquid is "insoluble." When a substance is classified as insoluble, it means that when mixed with a solvent, such as water, it does not form a solution. This is important because understanding solubility is crucial in pesticide application and formulation, determining how the pesticide can be effectively delivered and how it will behave in the environment.

For instance, when dealing with pesticides, certain active ingredients may be insoluble in water but could still be effective when absorbed through the plant’s leaves or applied in a different formulation. In contrast, soluble substances easily dissolve and can often be more readily absorbed or utilized by plants or organisms.

The other terms provided have distinct meanings that are not related to the idea of a substance’s inability to dissolve. "Soluble" refers to substances that can dissolve in a solvent, "aqueous" pertains to a solution in which water is the solvent, and "volatile" describes substances that can vaporize easily at room temperature. Thus, "insoluble" accurately characterizes substances that do not dissolve in liquids.