A perfect gas A. has constant viscosity B. is incompressible C. is of theoretical interest D. none of the above.

has constant viscosity
is incompressible
is of theoretical interest
none of the above.

The correct answer is: D. none of the above

A perfect gas is an idealized gas that obeys the ideal gas law. It is a theoretical concept that is useful for understanding the behavior of real gases. A perfect gas has no viscosity, is incompressible, and has no internal energy.

  • A perfect gas has no viscosity. This means that there is no friction between the molecules of the gas. This is an idealized condition, as real gases do have some viscosity.
  • A perfect gas is incompressible. This means that the volume of a perfect gas does not change with pressure. This is also an idealized condition, as real gases do compress under pressure.
  • A perfect gas has no internal energy. This means that the molecules of a perfect gas do not have any kinetic energy. This is also an idealized condition, as real gases do have some kinetic energy.

The ideal gas law is a mathematical equation that relates the pressure, volume, and temperature of a gas. The ideal gas law is given by the following equation:

$$PV = nRT$$

where $P$ is the pressure of the gas, $V$ is the volume of the gas, $n$ is the number of moles of gas, $R$ is the ideal gas constant, and $T$ is the temperature of the gas.

The ideal gas law is a good approximation for the behavior of real gases at low pressures and high temperatures. However, real gases do deviate from the ideal gas law at high pressures and low temperatures.