One crop is all they grow
The answer is: HIGH POROSITY.
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(although low permeability can be associated with greater water retention. Permeability can be affected by particular size. For instance, larger particular have larger poles, so fluid (water) can pass through water quickly (higher permeability and less water retention). As such, smaller particles have smaller pores, so fluid (water) can pass through water LESS quickly (lower permeability and RETAINING MORE WATER.).
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However, "high porosity" is the best choice.
I think that they can either use fossils or age of rocks
Answer:
<u>Iron </u>and <u>Nickel</u>
<u>core</u>
<u>Iron and Nickel</u>
Explanation:
Two of the most popular magnetic chemicals in the world are iron and nickel.
We can now match these metals with the description given in the question to check if they perfectly fit in the blanks.
The densities of iron and nickel are 7874kg/m3 and 8900kg/m3 respectively. To put this into perspective, the density of aluminium is only 2700kg/m3. This means that iron and nickel are really dense solid materials. These materials are strong enough to make the core of the earth.
Because these materials are also magnetic and strong, we can say that they are the materials that form the solid core of the earth's structure.
ANSWER : A.) mikhail gorbachev instituted social and political nations