Which statement is true about the characteristics of hot air compared to cold air?

Hot air is less dense than cold air due to the behavior of air molecules when they are heated. When air is warmed, the molecules gain energy and move faster, causing them to spread apart. This increase in molecular movement leads to a decrease in density, meaning that hot air occupies more volume than an equal mass of cold air. This principle is fundamental to understanding how hot air rises, creating convection currents that influence airflow and ventilation in spaces like attics.

The other statements do not accurately reflect the properties of hot and cold air. Saying that hot air is more dense or heavier than cold air is incorrect, as it contradicts the principles of thermodynamics. Additionally, the assertion that hot air is cooler than cold air directly contradicts the essence of what defines “hot” versus “cold” air. Recognizing these characteristics is crucial for understanding the implications they have on ventilation systems in buildings.