Answer:
F Anthracite (the hardest coal)
Explanation:
Coal is a sedimentary rock that is formed from plant materials. These plant materials must have been trapped and compacted in an environment where they are not able decay. Such an environment is a swamp.
The first grade of coal that forms initially in such an environment is called PEAT. Peat is soft coal that still contains some plant materials. It has a high moisture content and the amount of carbon is still quite low.
With increasing pressure and compaction, PEAT grades into LIGNITE which has more carbon atoms in it. Lignite is more combustible although it is quite soft too. Lignite grades into SUB-BITUMINOUS coal and then BITUMIOUS coal.
The highest grade of coal is ANTHRACITE which is a hard coal. It has very little moisture content and rich carbon percentage in it. Anthracite yields more energy compared to other forms of coal. Anthracite is basically coal that forms at the greastest pressure. Beyond this pressure, a metamorphic transformation occurs and the coals changes to graphite.
Based on increasing pressure:
PEAT< LIGNITE< BITUMINOUS COAL < ANTHRACITE
Answer:
Both explain how the movement of the Earth's crust occurs.
The correct answer for the given statement above would be TRUE. It is true that in 1066, William the Conqueror achieves political stability in England with the introduction of the feudal system. In addition, t<span>he system progresses over the next two centuries into a national monarchy. Hope this answers the question.</span>
Answer:
Explanation:
The two main categories of igneous rocks are extrusive and intrusive. Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.
The vertical trade is trade that essentially appears between people living in different elevations. In the Andean region, the vertical trade has a long history, and it has been performed between the people living in the higher parts of the Andes, and the people living in the valleys and coastal regions east and west of the Andes.
This type of trade helped the people to be able to survive and develop in both of those environments, as the people living high in the mountains were producing certain things, and the people living in the lowlands were producing certain things that both of them needed in their daily lives. Because they collaborated, they were able to create societies in totally different environments and thrive for centuries.
