Atoms adsorbed on a surface are often free to move over the surface and can be treated as an ideal two-dimensional "gas" Consider a 2-dimensional gas consisting of a single atom of mass m confined in a 2-D box of dimensions L by L (area L^2). (a) Derive expression for the partition function, Z, and internal energy, U, of this 2-dimensional atom gas in the classical (high T) limit. (b) Find the "spreading pressure" of 2D gas, defined as: P=1/*lnZ/A where A is the box's area. (c) Find the entropy, S, of the 2D atomic gas.