Why is electron affinity positive when the second electron is added to oxygen

If 15 drops of ethanol from a medicine dropper weigh 0.60g, how many drops does it takes from a dropper to dispense 1.0ml of ethanol? density of ethanol is ethanol is 0.80g/ml.

Why do the strengths of london (dispersion) forces generally increase with increasing molecular size? choose one: a. heavier atoms have stronger attractions for each other than lighter atoms. b. dispersion forces are all equal in magnitude; there is no size dependence. c. dispersion forces arise from the attraction between the nuclei of atoms, and larger molecules have larger nuclei. d. dispersion forces arise from dipoles caused by the electron distribution being distorted. larger molecules have more electrons and, therefore, more distortions and a bigger force. e. dispersion forces depend on distance. larger molecules are farther apart and so the forces are smaller.

Ms. sullivan's class is designing a miniature roller coaster. after first setting it up, they find that it didn't have enough speed to go through the loop de loop. instead of taking out the loop, they decide to increase the height of the first hill the coaster goes down, and this adds the speed needed to make it through the loop. what would be a drawback to this plan in real life? a) no one likes loop de loops. b) there is no downside to this plan. c) a higher hill means a scarier ride. d) a higher hill takes more time and material to build.