The purpose of a switch in a series circuit is to make it easy to open or close the electrical circuit, turning the flow of electricity on or off. A light bulb in a series circuit is used to determine whether or not electricity is flowing.
A molecule is defined as two or more atoms of the same element different element that are bound together. A molecule may be homonuclear, which means, it consists of atoms of one chemical element, as with oxygen (O2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (H2O).
You can boil the salt water. The water will evaporate while the salt will be left behind because it's a solid. Salt has a much higher boiling point than water (2,575° F), so that's why it won't evaporate with the water.