1. What number concentration of 0.05-um-diameter particles seatters as much light per cubic centimeter as 1 cm of particle-free air? Ge for air is 1.5x10im. Assume that m=1.5 for the particles and 23D0.5 um. 2. What is the visual range in particle-free air at 20 °C at sea level? Assume that 2=0.5 um. 3. If a saturation ratio of 4.0 is required for homogeneous nucleation. What is the minimum expansion ratio for adiabatic expansion of saturated water vapor at an initial temperature is 25 °C? 4. What is the partial vapor pressure of vapor at the droplet surface if the diameter of the droplet is 0.01 um at 293 K? 5. An aerosol of 0.01-um particles is taken at a rate of 0.2 L/min through a rectangular channel. The length, width, and height of the rectangular channel are 1.2 m. 0.01 m and 0.002 m, respectively. What fraction of the entering particles will lose in the channel?