The rough value of diffusion co-efficient of water vapor into air at 25°C may be about ______________ cm2/sec?

Related Mcqs:

1. At equilibrium the concentration of water in vapour phase (C*) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is_________________?

   A. 0.0
   B. 0.2
   C. 0.4
   D. 1.0

2. Ordinary diffusion process is also called ______________ diffusion?

   A. Pressure
   B. Thermal
   C. Concentration
   D. Forced

3. An air-water vapour mixture has a dry bulb temperature of 60°C and a dew point temperature of 40°C. The total pressure is 101.3 kPa and the vapour pressure of water at 40°C and 60°C are 7.30 kPa and 19.91 kPa respectively. The humidity of air sample expressed as kg of water vapour/kg of dry air is__________________?

   A. 0.048
   B. 0.079
   C. 0.122
   D. 0.152

4. The relation among various mass transfer co-efficients (M.T.C) for ideal gases is given by (where, Kc & Km are M.T.C. for equimolar counter diffusion with concentration & mole fraction respectively as the driving force. and, Kp= M.T.C. for diffusion of a gas through a stagnant inert gas with pressure as driving force) ?

   A. Kc = Kp = Km
   B. Kc = Kp/RT = Km . RT/P
   C. Kc = Kp . RT = Km . RT/p
   D. None of these

5. Diffusion co-efficient generally depends upon the temperature, pressure & the nature of the components of the system. Its dimension is not the same as that of the_________________?

   A. Mass transfer co-efficient
   B. Thermal diffusivity
   C. Kinematic viscosity
   D. Volumetric diffusivity

6. The diffusion co-efficient in m2/s. of acetic acid in benzene (liquid in liquid) is___________________?

   A. 2.09 × 10-4
   B. 2.09 × 10-5
   C. 2.09 × 10-9
   D. 2.09 × 10-12

7. Gaseous diffusion co-efficient increases with increase in the_____________________?

   A. Pressure
   B. Temperature
   C. Both A. & B.
   D. Neither A. nor B.

8. During dehumidification of unsaturated air wet bulb temperature & partial pressure of vapor are not constant. However, during evaporative cooling process with recirculated water supply, the _________________ remains constant ?

   A. Wet bulb temperature
   B. Partial pressure of water vapor
   C. Relative humidity
   D. None of these

9. Dew point of an air-water vapor mixture_________________?

   A. Decreases with decrease in pressure
   B. At constant humidity & total pressure is fixed
   C. Corresponding to any point on the humidity chart is obtained by projecting a line through this
   point parallel to the temperature axis and to the saturation curve
   D. All A , B. & C.

10. With increase in absolute humidity, the dew point of an unsaturated mixture of air and water vapor (at constant pressure and temperature) ?

    A. Increases
    B. Remains unchanged
    C. Decreases
    D. Decreases linearly