a) Assume you are evaporating Gold in a vacuum chamber of dimension 1 m x 1 mx 1 m. Residual air present after evacuating the chamber contains O and N, which can be assumed to be hard spheres. Their diameter is not very different, and so, for simplicity lets assume it is 3 A. Assume that the gas molecules are uniformly distributed in the chamber. The mean free path 1 is given by A-- - where, d is the diameter of the molecule and n is the 2ndn number density per unit volume. What pressure (in the units of Nm or Pascal) will you pump the chamber down to before you will evaporate gold? Why did you choose this pressure? Assume the gases follow ideal gas law, PV = nmoleRT, where, T is 300 K and R is 8.314 J molK, mole is the number of moles. The number of atoms or molecules (Avogadro Number) in 1 mole is 6 x 1023, atmospheric pressure is ~ 10 Nm.