Chlorofluorocarbon: Chlorofluorocarbon (CFC), any of several organic compounds composed of carbon, fluorine, and chlorine. When CFCs also contain hydrogen in place of one or more chlorines, they are called hydrochlorofluorocarbons, or HCFCs. CFCs are also called Freons, a trademark of the E.I. du Pont de Nemours & Company in Wilmington, Del. CFCs were originally developed as refrigerants during the 1930s. Some of these compounds, especially trichlorofluoromethane (CFC-11) and dichlorodifluoromethane (CFC-12), found use as aerosol-spray propellants, solvents, and foam-blowing agents.
The Egyptians started building the Great Pyramid of Giza on August 23, 2470 B.C., according to controversial new research that attempts to place an exact date on the start of the ancient construction project. Enlarge Photo. Printer Friendly. Email to a Friend.
The Great Pyramid of Giza was built around 2700 - 2500 BC. The Great Pyramid of Giza is in city of Giza, Egypt on the west bank of the Nile River, near Cairo. Out of all the Seven Wonders of the World, the Egyptian Pyramids are the oldest and only surviving wonders. No wonder they're wonders. (Okay, okay, that was a cheesy joke.) All three of the Great Pyramids are amazing but only the Great Pyramid of Khufu is considered a wonder. King Khufu of the Fourth Dynasty built the monument so he had a tomb to be buried in. It is said that the pyramid took over 20 years to construct.