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.
Despite popular belief, since 1982 pennies have only been copper plated, not copper through and through. Much less expensive zinc makes up 97.5% of the mass of a penny, the rest is a copper coating. Nickels actually have much more copper in them -- 75% copper and 25% nickel. It's the same mix they have always had except for the World War II years, when silver and manganese replaced the nickel and some of the copper.