Why should a liquid gas bottle only be filled to 80% of its volume?

Question

Question Quiz BPL Hot Air - Balloon Pilot License - Aircraft General Knowledge

QuizVDS · Accepted Answer

To provide space for temperature-induced expansion.

QuizVDS · Answer

Because temperature would get too high.

QuizVDS · Answer

Because it would get to heavy otherwise.

QuizVDS · Answer

To provide space for expansion in case of external cooling

BPL Hot Air: Why should a liquid gas bottle only be filled to 80% of its volume? Id: 81