Asystem consists of n identical particles, fixed in positions. each one can be in two states, one with energy 0 (not degenerate), and other with energy e > 0, with degeneracy g. suppose the system energy is e. (a) obtain an expression for the entropy s as a function of e (b) determine the occupations of energy levels, no and nɛ, at temperature t. (c) from now take g = 2, and plot a graph of s(e); comment if there are any differences from case g=1 (d) suppose now: (i) that the system has energy e = (3/4)ne, which corresponds to a temperature tsyst; (ii) the system is in contact with a thermal reservoir at a temperature tres; and (iii) that a certain amount of energy ae is exchanged with the reservoir (clearly state whether you consider that ae to be the energy the system gives in to the reservoir, or vice versa). obtain an expression for the total entropy variation, as = asres + assyst in terms of tsyst, tres, and ae. discuss the sign of ae and interpret.