Any series of operations so carried out that at the end,the system is back to its initial state is called:

Two moles of an ideal gas expand spontaneously into a vacuum. The work done is ............. $Joule$.

Exothermic reactions occur in which of the following processes?

The heat of combustion of ethanol in a bomb calorimeter at $25\,^oC$ is $-670.48\, K\,cal\, mol^{-1}$. Find the value of $\Delta U$ in $K\,cal$ for the reaction at $25\,^oC$.

When $2 \ L$ of an ideal gas expands isothermally into a vacuum to a total volume of $6 \ L$,what is the change in internal energy in $J$? (Nearest integer)

How will you calculate the work done on an ideal gas during compression,when the change in pressure is carried out in infinite steps?