Lower temperature and large excess of ammonia in urea melt__________________?

Related Mcqs:

1. Yield of urea can be increased with excess ammonia and higher pressure & temperature, but because of ____________ this is normally not done?

   A. Increased biuret formation
   B. High corrosion rate
   C. Increased cost of equipment
   D. All A., B. & C.

2. During conversion of ammonium carbamate into urea, presence of large excess of water______________?

   A. Increases the yield of urea
   B. Adversely affects the yield of urea
   C. Reduces the evaporator load by diluting the urea solution
   D. Does not affect the yield of urea

3. 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__________________?

   A. Low bulk density product
   B. Biuret formation
   C. Non-spherical prills
   D. Substantially wet non-flowing and sticky product

4. The composition of fresh feed to the high temperature, high pressure urea autoclave is______________________?

   A. Excess liquid ammonia and liquefied CO2
   B. Excess liquid ammonia and compressed CO2 gas
   C. Liquid ammonia and excess compressed CO2
   D. Compressed ammonia gas and excess compressed CO2

5. Temperature and pressure in urea autoclave is_________________?

   A. 120°C and 300 atm
   B. 190°C and 200 atm
   C. 400°C and 550 atm
   D. 200°C and 10 atm

6. Temperature and pressure in ammonia converter is_________________?

   A. 200 atm, 1000°C
   B. 450 atm, 200°C
   C. 450 atm, 550°C
   D. 450 atm, 1000°C

7. Though kinetics of ammonia synthesis dictates the use of low temperature for high equilibrium conversion, yet it is kept moderately high (550°C), because at low temperature___________________?

   A. Rate of reaction is very low
   B. Very high pressure is required resulting in costly pressure vessel
   C. Space velocity of gas is very low resulting in decreased conversion
   D. None of these

8. Urea is a better fertilizer than ammonium sulphate, because__________________?

   A. It is cheaper
   B. Nitrogen content is higher
   C. It is not poisonous
   D. It is easy to manufacture

9. Urea is formed only____________________?

   A. In liquid phase
   B. In vapour phase
   C. At very high temperature
   D. At very low pressure (vacuum)

10. Dehydration of ammonium carbamate to yield urea is a/an __________________ reaction?

    A. Exothermic
    B. Endothermic
    C. Autocatalytic
    D. Catalytic