Answer:
a single-replacement reaction replaces one element for another in a compound. A double-replacement reaction exchanges the cations, or the anions, of two ionic compounds.
This is because their tails are hydrophobic and their heads are hydrophilic. Hydrophobic meaning dislikes being near water and hydrophilic meaning likes to be near water. Therefore, they will orientate themselves in such a manner that the heads are facing externally and all the tails are facing together protected by the hydrophilic heads. google a photo of lipid chains in water if you are still confused. I'm not sure if that is what you are asking, but I hope it helps.
It’s the third one because Cl has 17 protons bc of the numeric number and 18 electrons bc it’s always the opposite and 18 neutrons because you subtract 35-17=18
