pH is defined as the concentration of hydrogen ions in aqueous solutions (i.e. the solvent is water), so by definition, gases and solids don't have a pH. read more
The matter is anything that has mass and occupies space. States of matter are the physical form taken by the phases of matter. Although the state and phase don't mean quite the same thing, you'll often hear the two terms used interchangeably. The States of Matter. States of matter are solids, liquids, gasses, and plasma. read more