<prompt> Which of the following is true about HPLC and gas chromatography?In Gas Chromatography, the stationary phase is always solidIn HPLC, the stationary phase is solidIn HPLC, the mobile phase is a liquid or solidIn Gas chromatography, the mobile phase is always gas  <response>: Ans. is d i.e., In gas chromatography, the mobile phase is always gasif a solute has an affinity for the mobile phase, it moves faster. If a solute has an affinity for stationary phase, it gets retarded.That way, the solutes get separated based on differential distribution of them between a mobile phase and a stationary phase. 