1. The multiplying factor, as applied to obtain the peak hourly demand, in relation to the maximum daily demand is:
A) 1.5
2. Coincident draft in relation to water demand is based on
C) Maximum daily + fire demand
3. Water is said to have one degree of hardness when its soap destroying power is equivalent to the effect of _______ of calcium carbonate in one litre of water
C) 14.25 mg
4. Hardness of water can be removed by boiling if it is due to
D) calcium bicarbonate
5. A water having pH value equal to 9 will have hydrogen ion concentration equal to
A) 10–9 moles / litre
6. The velocity of flow of water in a sedimentation tank is about
C) 150 to 300 mm/minute
7. Pick out the incorrect statement for a rapid sand filter:
(i) the period of cleaning is usually 2 to 3 weeks
(ii) the effective size of the sand particles is 0.35 to 0.6 mm
(iii) the maximum permitted loss of head is 3m
A) Only (i)
8. Which of the following chemical compounds can be used for dechlorination of water?
C) Sulphur dioxide
9. Which one of the following processes of softening water may require recarbonation?
A) Lime-soda process
10. As compared to rapid sand filters, slow sand filters are
A) more efficient in the removal of bacteria but less efficient in the removal of colour and turbidity
11. Grid iron system is best suited to
D) planned city on a gentle slope
12. In disinfection, which of the following forms of chlorine is most effective in killing the pathogenic bacteria?
D) HOCl
13. The Flavor Threshold Number (FTN) and Threshold Odour Number (TON) for the drinking water should not exceed
A) 3
14. In drinking water, the amount of free ammonia should not exceed
C) 0.50 mg/l
15. The maximum permissible total dissolved solidcontent in water for domestic purposes should not exceed
C) 500 mg/l
