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.
Breathe deeply into your abdomen, not just your chest. Proper breathing should be deep, slow and rhythmic and done through the nose, not the mouth. Each breath should ideally last three to four seconds breathing in and three to four seconds breathing out. Deep full breaths that fill your lungs use your diaphragm.