<span>Djenne-djeno is a cultural Heritage found in Mali. Djenne-djenno is a known cultural heritage because it was the first city center in sub-saharan part of Africa. In the past, people would often visit this place alongside their goods to trade with other traders.</span><span />
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
-Fertility rate: The factor which affects the growth of the population in the biggest way is the fertility rate.
-Mortality rate: A key factor affecting the growth of the population is the death, or mortality, rate. Just as the birth of new people increases the population size, deaths decrease it.
-Immigration and Emigration: Cross-border migration is the act of people moving from one country to another. It affects the population size of both the host and destination countries. Emigration is caused by a number of factors, such as fleeing war, finding education, seeking new jobs or joining family members. When a person emigrates from a country, its population shrinks.
