The chemical reaction for CFC is: CCl3F = CCl2F + Cl. Uses. Due to their chemical properties, CFCs became useful as coolants and propellants. More commonly known as freon for refrigeration, CFCs are used extensively in appliances as a safe method of refrigeration. The other main use for CFCs has been as a propellant for aerosol cans.
The earliest known Egyptian pyramids are found at Saqqara, northwest of Memphis. The earliest among these is the Pyramid of Djoser (constructed 2630 BCâ2611 BC) which was built during the third dynasty. This pyramid and its surrounding complex were designed by the architect Imhotep, and are generally considered to be the world's oldest monumental structures constructed of dressed masonry.
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.