1. A sphere with diameter D=25cm is placed within a cubical enclosure with a side length L=D. Calculate F12 and F21. 2. A stream of air at 100kPa pressure and 300K is flowing on the top surface of a thin flat sheet of solid naphthalene of length 0.2m with a velocity of 20m/sec. The other data are: Mass diffusivity of naphthalene vapor in air at this temperature and pressure =6106m2/sec Kinematic viscosity of air =1.5105m2.sc Concentration of naphthalene at the air-solid naphthalene interface = 1105kmol/m3 Calculate: (a) the overage mass transfer coefficient over the flat plate (calculate Re,Sh and Sc ) (b) the rate of loss of naphthalene from the surface per unit width