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.
Each time you take a breath, you inhale more than oxygen. The normal air in our environment consists of a few different gases. Approximately 78 percent of the air is nitrogen gas while only about 20.9 percent is oxygen. The remaining fraction is made up of primarily argon gas, but trace amounts of carbon dioxide, neon and helium are also present.