The molecular formula for carbon dioxide is CO₂, indicating that each molecule consists of one carbon atom bonded to two oxygen atoms. Carbon dioxide is a colorless, odorless gas that is naturally present in the atmosphere as a result of various biological and geological processes, such as respiration and volcanic activity. It plays a crucial role in the Earth's carbon cycle, serving as a key reactant in photosynthesis, where it is converted into glucose and oxygen by plants. Additionally, CO₂ is a significant greenhouse gas, contributing to global warming.