The Student Room Group

Exact differential - ideal gas law

For one mole of an ideal gas, the gas law is pV=RT
Write down the exact differential for the volume, dV.
The differential for the work, w, is given by dw=-pdV. Show that dw is not an exact differential.

Is there some kind of equation I can use to show whether or not a differential is exact? I'm not really sure about the first part because it doesn't seem to be asking to differentiate with respect to anything.
For a differential to be exact it must obey the Euler condition.