Question

Soft drink bottles are not filled up to the brim. A small gap is left between the surface of the liquid and the lid of the bottle. Why?

Answer 1

This is done as these drinks are carbonated and is left with a great pressure inside.when the cap Is opened the CO2 tries to escape rapidly which causes brisk effervescence or dizziness.this in turn has a chance to make the fluid overflow this is the reason for which there is a gap left.