What does vapor pressure indicate about a chemical?

Vapor pressure is a critical property that indicates the ease with which a chemical can evaporate into the atmosphere. It is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (liquid or solid) at a given temperature. A higher vapor pressure means that the substance has a greater tendency to convert into vapor, which directly correlates with its volatility.

For pesticides and other chemicals, understanding vapor pressure is important because it affects the behavior of the chemical during application, as well as its potential for drift and off-target effects. Chemicals with high vapor pressure can easily evaporate, which could impact environmental safety and efficacy of pest control methods.

The other choices do not accurately describe what vapor pressure indicates. Toxicity relates to the harmful effects of a substance on living organisms, stability under temperature changes involves the reactions or breakdown of a substance when exposed to heat, and pH level describes the acidity or basicity of a solution, none of which are directly associated with vapor pressure.