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.
It has been the past experience in the United States that when the melt value of a coin exceeds its face value, people will melt the coins in order to sell the raw metal and make a profit. In an effort to thwart a melt off of pennies in 1982, the United States Mint made half of the pennies out of solid copper and the other half out of copper plated zinc. Although it is illegal to melt pennies and sell the raw metal, people still pull the solid copper pennies out of circulation in order to save them for their copper value.