There are a lot of separation processes. To name a few, these can be distillation, centrifugation, extraction, membrane or sorption process and many other. To know which is the best technique, you should know the property between two substances that have a stark difference. In this case, it is the polarity. Ethyl alcohol is more polar than ethyl ester and less dense. Thus, these two won't mix. So, take advantage of their density difference by decantation or centrifugation.
This is the full question: what is the strongest intermolecular force in a liquid containing molecules with nonpolar bonds?
A. Covalent Bonds
B. Dispersion Forces
C. Hydrogen Bonds
D. none of these
This is the answer: B. Dispersion forces