In thermodynamic processes which of the following statements is not true?

• A

  In an adiabatic processes ${\mathrm{PV}}^{\mathrm{\gamma }}$ = constant.

• B

  In an adiabatic process the system is insulated from the surroundings.

• C

  In an isochoric process pressure remains constant.

• D

  In an isothermal process the temperature remains constant.