Replenishment of dissolved oxygen in water stream polluted with industrial waste occurs by________________?

Related Mcqs:

1. The amount of chemical coagulant added for treatment of polluted water ______________ with increase in temperature of the polluted water to be treated?

   A. Decreases
   B. Increases
   C. Remain constant
   D. May increase or decrease; depends on the chemical characteristics of polluted water

2. A butane isomerisation process produces 70 k.mole/hr of pure iso-butane. A purge stream removed continuously, contains 85% n-butane and 15% impurity (mole%). The feed stream is n-butane containing 1% impurity (mole%). The flow rate of the purge stream will be_________________?

   A. 3 kmole/hr
   B. 4 kmole/hr
   C. 5 kmole/hr
   D. 6 kmole/hr

3. Thermal pollution of water increases its toxicity and oxidation of oxygen demanding waste besides favouring bacterial growth. A rise in water temperature by 10°C, doubles the toxic effects of _____________ present in it?

   A. Coal ash
   B. Potassium cyanide
   C. Ortho-xylene
   D. None of these

4. Waste/polluted water discharged from electroplating, blast furnace and coal mining industries contain mainly _____________ substances?

   A. Radioactive
   B. Organic
   C. Inorganic
   D. None of these

5. Which of the following is the most efficient for removal of very finely divided suspended solids and colloidal matter from the polluted water stream ?

   A. Sedimentation tank
   B. Circular clarifier
   C. Mechanical flocculation
   D. Chemical coagulation

6. Pure oxygen is mixed with air to produce an enriched air containing 50 volume % of oxygen. The ratio of moles of air to oxygen used is_________________?

   A. 1.72
   B. 0.58
   C. 0.5
   D. 0.2

7. Radioactive substances present in the polluted water stream can be removed by_________________?

   A. Biological oxygen treatment
   B. Coagulation and filtration
   C. Adsorption in ion exchange materials
   D. None of these

8. Dissolved oxygen content in river water is around _____________ ppm?

   A. 5
   B. 100
   C. 250
   D. 500

9. For existence of aquatic life in water, the dissolved oxygen content in it, should not be less than ______________ ppm?

   A. 10000
   B. 5
   C. 500
   D. 1000

10. What fraction of the total pressure is exerted by oxygen, if equal weights of oxygen and methane are mixed in an empty vessel at 25°C ?

    A. 2/3
    B. 1/3
    C. 1/2
    D. 1/3 × (298/273)