Which of the following compounds is $NOT$ present in its standard state at $25^{\circ} C$ and $1 \text{ atmosphere}$ pressure?

If in a container neither mass nor heat exchange occurs,then it constitutes a

Calculate work done if $1 \ mole$ of an ideal gas expands isothermally from $2 \ dm^3$ to $2.8 \ dm^3$ against constant external pressure $1 \ atm$. (in $J$)

In thermodynamics,a process is called reversible when

Two moles of an ideal gas expand freely and isothermally from $5 \ dm^3$ to $50 \ dm^3$. What is the value of $\Delta H$?

When a system goes from state $A$ to state $B$,the change in internal energy is $40 \, kJ/mol$. If the system returns from state $B$ to state $A$ via a reversible path and then returns to state $A$ via an irreversible path,what is the net change in internal energy?