Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks as the minerals calcite and aragonite (most notably as limestone, which contains both of those minerals) and is the main component of pearls and the shells of marine organisms, snails, and eggs.
An ordinary breath for a 70-kg adult is about 500ml of air. We call this the tidal volume. Since oxygen is 21% by volume of air, then the volume of oxygen inhaled is about 105ml. The density of pure oxygen at sea level is 1.43kg per cubic metre.
The maximum volume of air that can be moved in and out of the lungs during a single breath; normally it is ~5.0 L; it is equivalent to the sum of the tidal volume, the inspiratory reserve volume, and the expiratory reserve volume; it varies depending on body size, fitness level, and degree of health or disease.