Final answer:
Water droplets form on the outside of a cold bottle of water on a hot day due to condensation.
Step-by-step explanation:
Water droplets form on the outside of a cold bottle of water on a hot day due to condensation.
Condensation occurs when water vapor in the air is cooled enough to form liquid water. Water droplets form on the outside of a cold bottle of water on a hot day due to condensation.
When the bottle is colder than the surrounding air, the water vapor in the air comes into contact with the cold surface of the bottle and condenses into liquid water droplets. Water droplets form on the outside of a cold bottle of water on a hot day due to condensation.
This process is similar to how condensation forms on the outside of a cold beverage glass or in the form of fog.