Materials GK Questions and Answers
1. How are diamonds cut?
Ans: Diamonds are cut with special diamond-bladed edges because they are very hard. Diamond cutting is an art, skill and, increasingly, a science of changing a diamond from a rough stone into a faceted gem. In relation to diamonds, cut has two meanings. The first is the shape: round, oval and so on. The second relates to the specific quality of cut within the shape. The most popular cut shape for diamonds is brilliant. This shape resembles that of a cone. Diamond cutting includes several steps like planning, cleaving or sawing, bruting, polishing, and final inspection.
Ans: Titanium toothbrushes, which were invented in Japan and now are being exported to the US, might help do away with toothpaste. One variety of the toothbrush uses titanium dioxide, which causes an electrochemical reaction while brushing and this helps remove plaque. The other type uses titanium bristles that last for several years.
3. What are white holes?
Ans: ??? White holes are the opposite of black holes in astrophysics, so much so that they eject matter and anti-matter instead of sucking them as with black holes. White holes appear as part of the vacuum solution to the Einstein field equations describing a Schwarzschild wormhole. One end of such a wormhole is a black hole, sucking in matter and the other end is a white hole, ejecting matter. The oscillations between the black holes at opposite ends of wormhole force the black holes to become white holes. It is stipulated that spiral arms of galaxies have been formed out of ejected matter from white holes. The origin of our Sun also lies in one of the spirals of the galaxy Milky Way.
4. Why are Eastern Crowned Cranes called so?
Ans: Eastern or Gray crowned cranes are named for their characteristic crown of gold feathers. They have a pale gray neck and red throat wattles. The rest of their bodies are black, white, and gold in colour. Gray crowned cranes are 39 to 43.3 inches tall and weigh anywhere from 6.6 to 8.8 pounds. They have a wingspan of between 71 and 79 inches. Gray crowned cranes are found in some areas of Eastern Africa. These are frequently found in trees. Individuals nest in wetland or grassland areas. Instead of building their own nests, Gray crowned cranes frequently use ground nests that have been abandoned by other large bird species
5. Why the plaster of Paris is called so?
Ans: Plaster is the common name for calcium sulphate hemi hydrate made by heating the mineral gypsum, the common name for sulphate of lime. Plaster was first made about 9000 years ago, and has been used by ancient Egyptian, Greek and Roman civilizations. However, it wasn?t used on a large scale until 1700s, when it was required to be used in all construction in Paris. In 1666, a fire raged across London, destroying many parts of it. In its aftermath, the king of France ordered that all walls made of wood in Paris be immediately covered with plaster, as a protection against such fires. This resulted in large-scale mining of gypsum which was available around Paris in huge quantities. Thus, during the early 18th century, Paris became the centre of plaster production, and hence the name, plaster of Paris.