North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere; it is also considered by some to be a northern subcontinent of the Americas
The process of forming the iron - rich core, the low density crust which is also rich in silicon, oxygen, aluminum, and the intermediate density mantle rich in silicon, oxygen, and magnesium is called the differentiation. Thus, the answer to this item is letter A.
When rocks and dust rub together
4 as the electronic configuration is 2,2 ! valence shells has 2 which is same as element 2 ( which i am assuming based on the periodic table is helium? )
Absolute age is the answer;)