Which state changes a vapor pressure?

Question

and how can a liquid or solid have a vapor pressure???

Answer 1

Although vapor and gas are frequently (incorrectly) used interchangeably, vapor refers to a gas phase in a state of equilibrium with identical matter in a liquid or solid state below its boiling point, or at least capable of forming solid or liquid at the temperature of the vapor. The term gas refers to a compressible fluid phase, as in common usage. Fixed gases are gases for which no liquid or solid can form at the temperature of the gas (such as air at typical ambient temperatures). A liquid or solid does not have to boil to release a vapor. The atmospheric boiling point of a liquid is the temperature at which the vapor pressure is equal to one atmosphere (unit).