A spherical bulb of 10−cm radius contains water vapor (gas) at 10 torr pressure and at 300 K. A small spot on the bulb wall having a surface area of 1 cm^2 is suddenly cooled with N2(ℓ), causing every water molecule to stick on this cooled surface upon striking. How long will it take for the water gas pressure to drop to 10^−4 torr?
