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 for the Fourth Dynasty Pharaoh Khufu (or Cheops), and was completed around 2560 B.C. It is part of a complex of 3 large pyramids in the Giza Necropolis located in modern Cairo, Egypt.The Great Pyramid is the largest of the three pyramids, and it is part of its own smaller complex that also contain 3 small pyramids that were built for Khufu's wives.It took approximately 20 years to complete, and several theories are debated by scholars as to how it was built and by whom.he Great Pyramid of Giza is the oldest monument on the list of the Seven Wonders of the Ancient World.