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 pyramids of Giza were built during the times when Khufu was the pharaoh. He ruled over Egyptâ¦ from 2551 BC to 2528 BC. Khufu had built the pyramids during 2560 BC. The pyramids took a period of more than 20 years to get complete from 2550 to 2530 BC and served as a tomb when Khufu died. Find more info at the link below.