I am really confused in my advanced chemistry class. We are currently doing intermolecular and intramolecular forces. For example, a book problem that has me frustrated is : "What is the strongest interaction between hexane and iodine?" What's the difference between "dipole-dipole" and "instantaneous dipole-dipole"? In general, how do you determine what intermolecular forces are at work when two molecules interact (ie, can a non-polar molecule still have dipoles?) Any help would be very much appreciated, because I am totally lost!