Plant material that accumulates and hardens on the floor of a swamp is
known as peat. if a layer of sediments accumulates on top of the peat, its
weight, after thousands of years, can compress the peat to form coal. which of the following types of coal probably
formed from the greatest pressure?
f anthracite (the hardest coal)
g bituminous coal (softer than anthracite)
h subbituminous coal (softer than bituminous)
j lignite (the softest coal)

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

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tension is the type of stress that results when two tectonic plates diverge .

explanation: