$A$ thermos flask containing some ice cubes is sealed tightly. This is an example of which type of system?

The work done during the expansion of $1 \ mol$ of an ideal gas into a vacuum is ............ .

$A$ system goes from $A$ to $B$ via two processes $I$ and $II$ as shown in the figure. If $\Delta U_1$ and $\Delta U_2$ are the changes in internal energies in the processes $I$ and $II$ respectively,then:

In thermodynamics,a process is called reversible when

For a cyclic process,what is true?

Which law of thermodynamics provides the definition of temperature?