The troposphere because it has half of all air in the Atmosphere
The biggest doubling time of all the regions/continents in the world has Europe.
Europe is the only continent that has almost 0% population growth (as of 2014), which practically means that with this pace Europe will need an eternity to be able to double its population, so it makes it the continent with the biggest time needed to double it's population.
The source of soil is called parent material.
I woild think if you were planning on traveling to that country you would want to know the exchange rate.
