For the isothermal expansion of a gas into a vacuum, E = 0, q = 0, and

For the isothermal expansion of a gas into a vacuum, ΔE = 0, q = 0, and w = 0.
(a) Is this a spontaneous process?
(b) Explain why no work is done by the system during this process.
(c) In thermodynamics, what is the "driving force" for the expansion of the gas?