A.) <span>Each molecule of hydrochloric acid, HCl, contains one atom of hydrogen and "One atom of Chlorine"
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Answer:
The correct answer is from areas of high concentration to low concentration.
Explanation:
A concentration gradient exists for these molecules, so they have the potential to diffuse into (or out of) the cell by moving down it.
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Answer:

Explanation:
A covalent bond involves the sharing of electrons to make the atoms more stable, and so they satisfy the Octet Rule (8 valence electrons).
Typically each atom contributes an electron to form an electron pair. This is a single bond. There are also double bonds (two pairs of electrons), triple bonds (three pairs of electrons), and coordinate covalent bonds.
Sometimes, to satisfy the Octet Rule and achieve stability, one atom contributes both of the electrons in an electron pair. This is different from other covalent bonds because usually each of the 2 atoms contributes an electron to make a pair.
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