Environmental Engineering Objective Questions - Set 09 - ObjectiveBooks

Environmental Engineering Objective Questions - Set 09

Practice Test: Question Set - 09


1. Which of the following compounds is widely used for algae control?
    (A) Sodium sulphate
    (B) Copper sulphate
    (C) Sodium chloride
    (D) Calcium chloride

2. Dissolved oxygen in streams is
    (A) Maximum at noon
    (B) Minimum at noon
    (C) Maximum at midnight
    (D) Same throughout the day

3. If the coli form bacteria is present in a sample of water, then the coli-form test to be conducted is
    (i) Presumptive coli-form test
    (ii) Confirmed coli-form test
    (iii) Completed coli-form test
    The correct answer is
    (A) Only (i)
    (B) Both (i) and (ii)
    (C) Both (i) and (iii)
    (D) All (i), (ii) and (iii)

4. As compared to higher pH values, the contact period required for efficient chlorination at lower pH values is
    (A) Smaller
    (B) Larger
    (C) Same
    (D) None of the above

5. Standard BOD is measured at
    (A) 20°C - 1 day
    (B) 25°C - 3 day
    (C) 20°C - 5 day
    (D) 30°C - 5 day

6. The velocity of flow of water in a sedimentation tank is about
    (A) 5 to 10 cm/sec
    (B) 15 to 30 cm/sec
    (C) 15 to 30 cm/minute
    (D) 15 to 30 cm/hour

7. Alum as a coagulant is found to be most effective when pH range of water is
    (A) 2 to 4
    (B) 4 to 6
    (C) 6 to 8
    (D) 8 to 10

8. The percentage of filtered water, which is used for backwashing in rapid sand filters, is about
    (A) 0.2 to 0.4
    (B) 0.4 to 1.0
    (C) 2 to 4
    (D) 5 to 7

9. For a country like India, where rainfall is mainly confined to one season, the suitable sewerage system will be
    (A) Separate system
    (B) Combined system
    (C) Partially combined system
    (D) Partially separate system

10. If the time of concentration is 9 minutes, then the intensity of rainfall according to British Ministry of Health formula will be
    (A) 4 mm/hr
    (B) 10 mm/hr
    (C) 20 mm/hr
    (D) 40 mm/hr

11. The minimum and maximum diameters of sewers shall preferably be
    (A) 15 cm and 100 cm
    (B) 15 cm and 300 cm
    (C) 30 cm and 450 cm
    (D) 60 cm and 300 cm

12. Sewage treatment units are designed for
    (A) Maximum flow only
    (B) Minimum flow only
    (C) Average flow only
    (D) Maximum and minimum flow

13. When there is no recirculation of sewage, then recirculation factor is
    (A) 0
    (B) 1
    (C) Infinity
    (D) None of the above

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