The Arenal Volcano in Costa Rica
In the periodic table, the atomic radius of the atoms decrease from left to right. This means that Carbon is smaller than Boron. So from the choices you can rule out the first and third choice.
Now, the reason why Carbon is smaller than Boron is because Boron has more protons and as the protons increase it attracts the electrons closer, which makes the atom smaller.
Carbon has more protons, so it exerts a greater pull. The answer is then Option 2: Boron has a larger radius and the protons in carbon exert a greater pull.
As for the second question, a compound is defined as a substance that is made up of two DIFFERENT elements that are chemically bonded. If you look at the second option, it is a compound. It is made up of hydrogen and oxygen atoms.
The answer is then option 2.
The perivascular feet of the <u>endothelial cells</u> help create a blood-brain barrier.
<h3>What are endothelial cells?</h3>
Endothelial cells can be defined as those type of cells found in the inside lining of blood vessels, lymph vessels, and the heart.
Interestingly, the major function of the edothelial cells is that they release substances that control vascular relaxation and contraction as well as enzymes that control blood clotting, immune function and platelet (a colorless substance in the blood) adhesion.
So therefore, the perivascular feet of the endothelial cells help create a blood-brain barrier.
Learn more about endothelial cells:
brainly.com/question/7448518
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