What happens if propane is not stored upright?

When propane is not stored upright, it becomes unstable and may leak. Propane exists as a liquid under pressure in storage tanks and requires proper positioning to maintain its safe and stable containment. When a tank is stored on its side or at an improper angle, the pressure inside can cause the liquid to rise to openings not designed for that purpose, leading to possible leaks of propane gas, which can pose safety hazards such as fire risks or explosions.

The other choices do not accurately describe the implications of improper storage. For instance, storing propane upright is essential for maintaining its combustibility; therefore, the assertion that it loses combustibility is unfounded. Similarly, propane does not evaporate quickly merely due to its storage position, nor does it change its chemical composition based on orientation. Thus, the correct choice highlights the critical safety aspect associated with the proper storage of propane.