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It is used by plants in the process of [[photosynthesis]] to generate [[oxygen]].

It is used by plants in the process of [[photosynthesis]] to generate [[oxygen]].

At room temperature, it is a gas. It becomes solid at -78 ºC, forming dry ice. When it thaws, it turns directly into a gas again (see [[sublimation]]). <ref>"Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid." [http://www.howstuffworks.com/question264.htm How Stuff Works] </ref>

At room temperature and atmospheric [[pressure]], it is a gas. It becomes solid at -78 ºC, forming dry ice. When it thaws, it turns directly into a gas again (see [[sublimation]]). <ref>"Dry ice is frozen carbon dioxide. A block of dry ice has a surface temperature of -109.3 degrees Fahrenheit (-78.5 degrees C). Dry ice also has the very nice feature of sublimation -- as it breaks down, it turns directly into carbon dioxide gas rather than a liquid." [http://www.howstuffworks.com/question264.htm How Stuff Works] </ref>

Each molecule of carbon dioxide has one carbon atom and two oxygen atoms, so its chemical formula is  CO₂.

Each molecule of carbon dioxide has one carbon atom and two oxygen atoms, so its chemical formula is  CO₂.