When \( 2 \, \text{litre} \) of ideal gas expands isothermally into vacuum to a total volume of \( 6 \, \text{litre} \), the change in internal energy is ________ \( \text{J} \). (Nearest integer)
Arrange the following isothermal processes in order of the magnitude of the work \\( (p - V) \\) involved between states \\( 1 \\) and \\( 2 \\).
(A) Expansion in single stage \\( w_A \\)
(B) Expansion in multi stages \\( w_B \\)
(C) Compression in single stage \\( w_C \\)
(D) Compression in single stage \\( w_D \\)
