🔍 Key Concepts

• Basic physics of liquids and gases in a closed container • Definition of vapor vs. liquid and the gas above a liquid • How equilibrium is reached between evaporation and condensation in a sealed space

💭 Think About

• Ask yourself: what do we call the pressure created by molecules that have left the liquid and are moving around as gas in the space above the liquid? • Which term is commonly used in chemistry and cargo-handling to describe how volatile a liquid is at a given temperature? • Which answer choice is a standard scientific term you’ve seen in textbooks, not just general language from cargo operations or safety?

✅ Before You Answer

• Verify which term specifically refers to the pressure of a substance’s own vapor in a closed container at a given temperature. • Eliminate any terms that mainly relate to tank safety conditions (like excess pressure or emergency relief) rather than a basic physical property of a liquid. • Check which choice you’ve seen associated with cargo data sheets, such as: "flash point, boiling point, ________" for liquids.