Since the thermal conductivity of still air [0.025 W/(moC)] is much smaller than the thermal conductivity of glass [0.80 W/(moC)], the temperature difference across the double pane window is almost entirely over the air gap. (Again, in this steady state, the rate of heat flow through the glass and air are the same for the double pane window, so if the conductivity of air is much smaller than that of glass, the temperature difference across the air must be much larger than that across the glass for these windows.) Considering this, what is the ratio of the rate of heat flow through a cheap window with a single pane of glass 5-mm thick compared to a nicer double pane window with an air gap of 5 mm if the temperature difference across them is the same (and they have the same areas)