If a radiographic substance's half-life is 20 years, how much of a 40 gram sample will be left after 60 years?
A. 5 grams
B. 10 grams
C. 20 grams
D. 30 grams

A because 60 divided by 20 is 3 so it is going through 3 stages of half life. 40/2=20 which is one half life then 20/2=10 which is the second half life then 10/2=5 which is the 3rd and final half life

Humid continental climate is found in the interior of continents between the 30 and 60 degrees latitude, but usually above the 40 degree line.   40 degrees north of the equator means less direct sunlight and therefore less warmth.   this climate is mainly found in the northern hemisphere since there are no major landmasses in the southern hemisphere.  if you live in northern indiana, you know all about humid continental because that is the climate type you have!

The enviroment with hedge hogs