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.
A penny is not what you think. Indeed, from 1783 to 1837, a cent was pure copper. But newer pennies are made mostly of zinc. Here's the history, according to the U.S. Mint: 1  From 1837 to 1857, the cent was made of bronze (95 percent copper, and five percent tin and zinc). 2  From 1857, the cent was 88 percent copper and 12 percent nickel, giving the coin a whitish appearance.