A Dewar bottle is a double-walled glass container whose interiorhas been made empty. These containers are generally used toconserve substances at very low temperatures
a) If the vacuum pressure is 1.00 Pa, calculate the mean freepath of the enclosed molecules between the walls of the Dewar at atemperature of 220 K, taking an effective value of 0.4nm2 for the cross section.
b) What is the frequency of collision between the molecules ofthis gas?
c) What is the purpose of the vacuum between the walls of thisvessel?
