copper

Copper is a reddish-orange metal. It is one of the most common and useful known metals to man. In nature, copper is found in two forms -as "native," or pure , copper and in mineral ores, combined with other elements. Because it can be found in a pure form, copper was probably one of the first metals ever used by man.

            There are more than 160 known mineral ores that contain copper. About half of the world's copper supply is found in a bright -yellow mineral called chalcopyrite. This ore is a compound of copper ,. iron, and sulfur. It contains 34.5 percent copper. One of the richest copper ores, chalcocite, is dark-gray and contains about 80 percent of copper.

            Copper has a number of interesting properties that make it useful to man. It is a soft, or malleable, metal that can be beaten or rolled to make thin sheets. Copper is also very ductile. That is, very long wires of different thickness can be drawn from copper. Copper conducts heat well, which is why cooking vessels and boilers are often made of copper. Finally, copper is one of the best conductors of electricity. In fact, most of the world's production of copper is used by the electrical industry.

            Brass is an alloy of copper, made by adding zinc to copper. Brass is used to make a variety of different objects. Door handles, screws, and electrical fittings are only a few examples of the hundreds of items made by brass. Brass has an attractive golden- yellow color, but it tarnishes easily and therefore requires constant cleaning.

            When tin is added to copper, another important alloy called bronze is formed. Bronze has a yellowish-brown color. Bronze is used to make tableware, bowls and other decorative objects.

1.One of the richest copper ores is__________.

     a) iron      b) chalcocite        c) chalcopyrite               d) sulfur

    

2. The underlined word "malleable" in paragraph ( 3) is closest in meaning to which of the following?

      a)  reddish –orange              b) thick               c) alloy               d) soft

3. Because copper is ductile, it can be__________..

     a) used to make cooking vessels

      b) drawn into long wires

      c) beaten or rolled into thin sheets .

      d) used to make alloys..

4  .Brass is  an alloy of __________.

     a) copper and zinc      b) copper and tin

      c) brass and tin        d) copper and iron

 5. What is the main idea of the passage ?

     a) Copper is one of the most common and useful metals.

     b) More than 160 mineral ores contain copper.

     c) Copper is mainly used by electrical industry..

     d) Copper is a reddish-orange metal.