Explanation:
Hey there!!
An elements is called a pure substance because it is composed of only one kina of atoms in a fix proportion.
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The amount of energy lost at the transition between each trophic level of the pyramid of energy is about 90%.
There are a total of 4 trophic levels.
The producers which bare plants represent the first trophic level. Herbivores represent the second trophic level. Carnivores represent the third trophic level. Top carnivores represent the fourth trophic level.
The 10 % rule is followed by the energy flow in a food chain. It means that moving from one trophic level to another, only 10% of energy is transferred and the rest is lost in the atmosphere.
So the 90% percent energy is lost at the transition between each trophic level of the pyramid of energy.
If you need to learn more about the trophic levels, click here
brainly.com/question/13267084
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Well the US doesn't naturally have a lot of fossil fuels so we rely on other countries who do have fossil fuels. So if we aren't that friendly with Saudia Arabia (they have a bunch of oil) then they can hike up the prices or cut us off from their oil supply completely which would cripple the US severly. So with that being said, we NEED other countries, and the big question is when will they not NEED us. At any point in which they feel that they don't need us they can just cut us off, which would be bad.
Hope that helps :)