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Chemical Engineering :: Environmental Engineering

  1. Threshold limit value (TLV) means maximum permissible/acceptable concentration. TLV of phosgene in air is about __________ ppm (parts per million).

  2. A.
    0.002
    B.
    0.2
    C.
    1.2
    D.
    4.8

  3. The density of the gases (present in air) decreases with increasing altitude to such an extent, that about 70% of the mass of atmospheric air is found in the lower 5 km. of the atmosphere. This lower region of atmosphere is called the

  4. A.
    ionosphere
    B.
    troposphere
    C.
    stratosphere
    D.
    none of these

  5. Biological oxidation ponds remove organic matters present in the polluted water by

  6. A.
    using the activities of bacteria and other micro organisms.
    B.
    aerobic oxidation.
    C.
    both (a) & (b).
    D.
    neither (a) nor (b).

  7. Which of the following is an adsorbant for removal of nitrogen oxides from gas/air ?

  8. A.
    Active carbon
    B.
    Silica gel
    C.
    Bog iron (iron oxide)
    D.
    Pulverised limestone

  9. Out of the following, TLV of __________ is the minimum (about 0.02 ppm).

  10. A.
    phosgene
    B.
    bromine
    C.
    MIC (methyl iso-cynate)
    D.
    ozone

  11. The average thickness of ozone layer in stratosphere is about __________ dobson unit (DU).

  12. A.
    20
    B.
    230
    C.
    750
    D.
    1500

  13. Polyvinyl chloride containers are not suitable for storing

  14. A.
    foodstuffs
    B.
    woolen clothes
    C.
    metallic powder
    D.
    none of these

  15. Presence of nitrogen in high concentration in contaminated air reduces partial pressure of oxygen in lungs, thereby causing asphyxia (suffocation) leading to death from oxygen deficiency. Concentration of N2 in contaminated air at which it acts as a natural asphyxant is ≥ __________ percent.

  16. A.
    84
    B.
    88
    C.
    80
    D.
    92

  17. TLV of ammonia, nitrogen dioxide and phenol vapor in air is __________ ppm.

  18. A.
    5
    B.
    100
    C.
    1000
    D.
    2000

  19. Corrosion in boilers can be prevented by

  20. A.
    deaeration of feed water.
    B.
    enhancing pH of feed water by adding alkali.
    C.
    feeding sodium sulphite or hydrazine phosphate to the boilers, which combines with oxygen and prevents corrosion.
    D.
    all (a), (b) and (c).