Amount of a substance (called the solute) that dissolves in a unit volume of a liquid substance (called the solvent) to form a saturated solution under specified conditions of temperature and pressure.Solubility is expressed usually as moles of solute per 100 grams of solvent.
There was no specification on the units of volume. However, whatever it may be, just replace the square brackets with the value and your units will be correct.
As the diaphragm contracts and flattens, it increases the volume of the thorax where the lungs are located. This results in a decrease in pressure (Boyle’s Law, if you know it) that creates a pressure gradient from outside to inside. This is what causes air to move into the lungs.