Which one of the following is not a state function?

What will be the difference in heat at constant pressure and constant volume for the combustion of carbon monoxide at $27 \, ^oC$ in $cal$?

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

For a massless piston undergoing an expansion of $\Delta V$ at constant temperature against a variable external pressure $P$,which equation represents the work done?

Find the work done on $2 \ mol$ of an ideal gas at $27^{\circ} C$ if it is compressed reversibly and isothermally from $5.05 \times 10^6 \ Nm^{-2}$ to $1.01 \times 10^5 \ Nm^{-2}$ pressure. (in $kJ$)

The value of $\Delta H - \Delta E$ for the following reaction at $27 \ ^\circ C$ will be $2NH_{3(g)} \to N_{2(g)} + 3H_{2(g)}$