The rate at which the properties of one of these substances change can be defined in terms of a lapse rate. The derivation of one law that approximately describes them takes the net impulse due to a collision with a wall to be exactly twice a particle's normal momentum; that assumption is part of kinetic molecular theory. The Maxwell-Boltzmann distribution describes the speeds of individual particles in these substances. A constant named for these substances is a macroscopic version of Boltzmann's constant, and takes on a value of 8.31 in standard SI units. Ideal ones are described by the law 
The rate at which the properties of one of these substances change can be defined in terms of a lapse rate. The derivation of one law that approximately describes them takes the net impulse due to a collision with a wall to be exactly twice a particle's normal momentum; that assumption is part of kinetic molecular theory. The Maxwell-Boltzmann distribution describes the speeds of individual particles in these substances. A constant named for these substances is a macroscopic version of Boltzmann's constant, and takes on a value of 8.31 in standard SI units. Ideal ones are described by the law "P V equals n R T". For 10 points, name this least-dense state of matter.
The rate at which the properties of one of these substances change can be defined in terms of a lapse rate.