A 50 kg hot iron block is dropped into a relatively cold lake at temperature T. During thermal equilibrium the lake receives Q amount of heat from the iron block. Show that the entropy change of the lake is Q/T starting with an expression for the specific entropy change of an incompressible liquid which is C ln(T2/T1), where C is the specific heat, and T1 and T2 are the initial and final temperature of the liquid due to heat transfer. State any assumptions that you make.