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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