288. Raw water treated with only chlorine, is known as
A. plain chlorination
B. pre-chlorination
C. first-chlorination
D. de-chlorination
289. Plain chlorination is used for water
A. with turbidities less than 20 mg/litre
B. obtained from clear lakes
C. consumed during emergencies
D. all the above.
290. For plain chlorination of water, the quantity of chlorine used, is
A. 0.1 mg/litre
B. 0.2 mg/litre
C. 0.3 mg/litre
D. 0.5 mg/litre.
291. Standard process of chlorination of water, is done by
A. plain chlorination
B. pre-chlorination
C. post-chlorination
D. double chlorination.
292. At break point of chlorination,
A. chlorine is used to oxidise
B. residual chloride is zero
C. residual chloride is maximum
D. residual chlorine reappears.
293. De-chlorination is followed by
A. post-chlorination
B. pre-chlorination
C. double-chlorination
D. super-chlorination.
294. The most commonly used chemical for dechlorination of water, is
A. sodium thiosulphate
B. sodium bisulphate
C. sodium sulphite
D. sulphur-dioxide
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