Explanation:
an air mass is a body of air with relatively constant temperature and moisture content over a significant altitude are message typically covered hundreds thousands or millions of square kilometres a front is the boundary at which two air masses of different temperature and moisture content meet
The correct answer is - plate tectonics.
The convection currents in the mantle, are having very high temperatures and very high pressures. Because of that, they managed to crack the crust, and thus divide the surface of the Earth in multiple peaces, or as we call them, tectonic plates. The very high pressure from bellow manages to push the tectonic plates in certain direction, and even though that movement is only a couple of cm per year, on the long term it has huge effects on everything on the planet.
The Spanish people colonist was
interdependent
Set this up as
10 = 40 (1/2)t/28
and solve for t in years.
10/40 = (1/2)t/28
log(0.25) = (t/28) log(0.5)
t = 28 log(0.25) / log(0.5) years = 56 years
Test the answer:
56 years = 2(28 years) = 2 half-lives, so the remaining amount should be 1/2 of 1/2 of the initial amount, i.e. 1/4 of the initial amount, and 10 mg = 1/4 of 40 mg.