Population tables. of world cities. This article lists the most populous cities in the world defined according to a concept of city proper. A city proper is a locality defined according to legal or political boundaries and an administratively recognised urban status that is usually characterised by some form of local government. Cities proper and their boundaries and population data may not include suburbs. World Urbanization Prospects, a UN publication, defines population of a city proper as the population living within the admi
The mass of one cubic centimeter of copper is 8.96 grams, while the mass of the same amount of zinc is 7.13 grams. 1  A penny is made of copper and zinc. 2  Copper is heavier than zinc. 3  The cost of copper has been on the rise during the past couple of decades.
Since it resists corrosion from the air, moisture and seawater, copper has been widely used in coins. Although once made nearly entirely from copper, American pennies are now made from zinc that has been coated with copper. Copper is also used to make water pipes and jewelry, as well as other items. Pure copper is usually too soft for most uses. People first learned about 5,000 years ago that copper can be strengthened if it is mixed with other metals. The two most familiar alloys of copper are bronze and brass.