Question

This long tube connects the mouth to the stomach

Answer 1

That would be the esophagus. It is a long tube that connects the mouth to the stomach. Food goes down it and ends up in the stomach where acids break it up into things that need to be kept in the body. The things that are kept are used for energy and nutrients for the body to use in every day use. 

Answer 2

Esophagus is the answer....hope this helps