You get a cooling effect when acetone is placed on your nails. why is placing acetone on your nails an endothermic process? heat from the body is absorbed by acetone as it evaporates. heat is released into the body by acetone as it evaporates. acetone has a lower temperature than the surroundings. the temperature of the surroundings is greater than acetone. there is no exchange of energy between acetone and the surroundings.

                 Heat from the body is absorbed by acetone as it evaporates.

                        In order to understand this question you should get familiar with evaporation, endothermic and exothermic processes.

                        Evaporation is the process in which the molecules of solvent continuously escapes from the surface of that solvent. Therefore, those molecules which are energetic, having greater kinetic energy leaves the system and the system is left with molecules with lower energy hence, causes cooling.

                         While, Endothermic process is that process in which the system absorbs heat and in Exothermic process the system releases heat. Hence, for evaporation the solvent requires heat and is therefore endothermic in nature.

                          In case of acetone on nail, the highly energetic molecules of acetone escapes leaving behind lower energy molecules which in return absorbs energy from body causing cooling effect.

you need to have a picture of the atom that way we can answer it

4d^55s^1 ( third choice)