Does the amount of precipitation in each tube indicate that all the acid impurity has been removed from the ether layer containing the unknown neutral compound

Precipitation reaction is a chemical reaction used to separate the insoluble solid to the aqueous solution. This is a technique that is usually used to separate the impurities. By knowing the right chemical to react with, only the pure acid will react and dissolve with ether. The impurity will be precipitated and will settle to the bottom.