Why a Chest Tube is Placed. A chest tube is placed for a variety of reasons. One reason, as you mentioned, is to help the lung re-inflate when someone has a collapsed lung, also known as a pneumothorax. In that circumstance, a chest tube is inserted along the side of the ribs to allow the lung to reinflate.
A. Osmosis is the passive movement of water from an area high in water concentration, across a semi-permeable membrane, to an area low in water concentration.
Osmosis is movement of water from a dilute solution to a concentrated solution through a semi-permeable membrane. The gases like oxygen and carbon-di-oxide get exchanged between the outside and the internal environments by diffusion. Movement of dissolved food molecules is also based on diffusion.