Question

why we feel cool when putting a drop of perfume on our palm

Answer 1

perfume is a volatile liquid and have a very low boiling point that's why it evaporates rapidly with heat of our palm

Answer 2

When we put some perfume on our hands because perfume is having higher evaporation rate.Thus when it evaporates it takes the energy from our hands in the form of LATENT HEAT OF VAPOURIZATION .Thus we feel cool.