Prilling of urea should be accomplished (in a sprayer) just above the melting po

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Question
Prilling of urea should be accomplished (in a sprayer) just above the melting point of urea with minimum of retention time, otherwise it will result in
Options
A. low bulk density product
B. biuret formation
C. non-spherical prills
D. substantially wet non-flowing and sticky product

Correct Answer

biuret formation

1. Pure aniline is evaporating through a stagnant air film of 1 mm thickness at 300 K and a total pressure of 100 KPa. The vapor pressure of aniline at 300 K is 0.1 KPa. The total molar concentration under these conditions is 40.1 mole/m³ . The diffusivity of aniline in air is 0.74xl0^-5m²/s.The numerical value of mass transfer co-efficient is 7.4 x 10^-3. The rate of evaporation of aniline is 2.97 x 10^-4. Its units are
Options
A. mole/s
B. mole/cm². s
C. mole/m² . s
D. kmole/m² . s

2. The heat of adsorption of a gas caused by Van der Walls forces of attraction and capillarity is equal to the heat of
Options
A. normal condensation.
B. wetting.
C. sum of (a) and (b).
D. difference of (a) and (b).

3. Under conditions of equal reduced pressure and equal reduced temperature, substances are said to be in the 'corresponding states'. At equal reduced conditions i.e., at the corresponding state, the __________ of different gases are nearly the same.
Options
A. compressibility
B. molecular weight
C. humidity
D. none of these

7. The main function of a muffle in the muffle furnace is to
Options
A. protect the charge from the effects of the products of combustion.
B. smooth out temperature inequalities on the combustion side of the muffle wall.
C. both (a) & (b)
D. neither (a) nor (b)

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