To test chemical oxygen demand (C.O.D.) of sewage, organic matter is oxidised by potassium dichromate in the presence of_______________?

Related Mcqs:

1. For the COD test of sewage, organic matter is oxidised by K2Cr2O7 in the presence of________________?

   A. H2SO4
   B. HNO3
   C. HCl
   D. None of these

2. In sewage having fully oxidised organic matter, the nitrogen exists in the form of________________?

   A. Nitrites
   B. Nitrates
   C. Free ammonia
   D. Aluminoid nitrogen

3. If a 2% solution of sewage sample is incubated for 5 days at 20°C and the dissolved oxygen depletion was found to be 8 mg/l. The BOD of the sewage is_________________?

   A. 100 mg/l
   B. 200 mg/l
   C. 300 mg/l
   D. 400 mg/l

4. If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is_____________________?

   A. 50 ppm
   B. 100 ppm
   C. 150 ppm
   D. 200 ppm

5. If the depletion of oxygen is found to be 2.5 mg/litre after incubating 2.5 ml of sewage diluted to 250 ml for 5 days at 20°C, B.O.D. of the sewage is_________________?

   A. 50 mg/l
   B. 100 mg/l
   C. 150 mg/l
   D. 250 mg/l

6. If 2% solution of a sewage sample is incubated for 5 days at 20°C and depletion of oxygen was found to be 5 ppm, B.O.D. of the sewage is____________________?

   A. 200 ppm
   B. 225 ppm
   C. 250 ppm
   D. None of these

7. The sewage treatment units in which anaerobic decomposition of organic matter is used, are called________________?

   A. Imhoff tanks
   B. Trickling filters
   C. Sludge sedimentation tanks
   D. None of these

8. The density of population over 40 hectares is 250/hectare. If water supply demand per day is 200 litres and sewage discharge is 80% of water supply, the sewage flow in sewers of separate system, is_____________________?

   A. 0.05552 cumec
   B. 0.05554 cumec
   C. 0.05556 cumec
   D. 0.0556 cumec

9. Bio-chemical oxygen demand (BOD) for the first 20 days in generally referred to_______________?

   A. Initial demand
   B. First stage demand
   C. Carbonaceous demand
   D. All of these

10. Lead acetate test in sewer manhole is done to test the presence of ____________________?

    A. Methane gas
    B. Hydrogen sulphide
    C. Carbondioxide gas
    D. Diesel vapours