Answer:
<em>A. 6,000 years</em>
Explanation:
Original sample N = 60 g
The half life of N/2 is 3000yrs
"""""""""""""""""""N/4 is 6000yrs
N/4 ===> 15 gram
it takes 6000yrs to decrease to 15grams
Polar.
The polar regions are cold year round because of the chill, polar air has a low capacity to evaporate water vapor in the air. The sun angle is fairly low throughout the year in polar areas. A significant amount of solar radiation that does reach the polar surface is reflected back into space.
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The corona is an envelope of ionized gases that extends out past the sun.
The corona is the third layer of the Sun. This layer takes the out most portion of the Sun's atmosphere. It is consisted of ionized gases that normally extend around one million kilometers from the Sun's surface.
Answer: Global wind patterns affect how air masses move. Prevailing westerlies are the major wind belts in the continental United States. The prevailing westerlies generally push air masses from west to east. For example, continental polar masses from central Canada enter the United States between the Rocky Mountains and the Great Lakes. These cold, dry air masses are blown east and affect the weather in the central and eastern part of the United States.
Explanation:
The land was shaped like a crescent and the soil there was fertile.