1. Refraction is the process of natural ___ of light.
a) shining b) dissolution c) bending
2. When light passes through a prism, one can see different ___.
a) pictures b) colours c) movies
3. A rainbow is light passing through ___.
a) elementary particles b) a mountain c) droplets of water
Text 3. Where Does Metal Come From?
Most metal is mined straight out of the earth in the form of ore. Ore is any part of the Earth’s crust, often a mixture of rocks, loose soil and other earthy materials, from which a valuable material can be extracted. This can be difficult, since the desirable metal is often locked in chemical compounds with other unwanted materials and filled with impurities. Ore refiners must find the best way to separate each useful element from the rest of the ore in which it lies. One common method of extraction is smelting, which is where refiners heat the ore to extremely high temperatures with the use of powerful furnaces. This makes it easier to get the pure metals out. In the refining of iron, for instance, the smelting process releases unwanted particles of oxygen that populate raw iron ore.