51.00.00 Physics of gases
- 51.10.+y Kinetic and transport theory of gases (see also 05.20.Dd Kinetic theory in classical statistical mechanics; see also 47.70.Mc Radiation gas dynamics) (1)
- 51.20.+d Viscosity, diffusion, and thermal conductivity (1)
- 51.30.+i Thermodynamic properties, equations of state (see also 05.70.Ce Thermodynamic functions and equations of state in thermodynamics)
- 51.35.+a Mechanical properties; compressibility
- 51.40.+p Acoustical properties (see also 43.28.-g Aeroacoustics and atmospheric sound in Acoustics Appendix; for ultrasonic relaxation in gases, see 43.35.Fj- in Acousics Appendix)
- 51.50.+v Electrical properties (ionization, breakdown, electron and ion mobility, etc.) (see also 52.80.-s Electric discharges in physics of plasmas)
- 51.60.+a Magnetic properties
- 51.70.+f Optical and dielectric properties; Sorption, see 68.43.-h; Gas sensors and detectors, see 07.07.Df (1)
- 51.90.+r Other topics in the physics of gases (restricted to new topics in section 51)