Hot Air Balloon: The Science Behind Its Flight

1. What is the primary gas used to fill a hot air balloon?

A. Nitrogen

B. Helium

C. Oxygen

D. Hydrogen

Answer:

The correct answer is B. Helium.

Hot air balloons rely on helium to achieve flight. Helium is a lighter-than-air gas that is commonly used to fill hot air balloons. When heated, the helium inside the balloon expands and becomes less dense than the surrounding air, causing the balloon to rise. This principle is known as buoyancy, where the hot air balloon is lifted because of the difference in densities between the helium-filled balloon and the cooler air outside.