Related Questions

A. some towns in Bangladesh are polluted B. All polluted towns should be destroyed C. Town Dhaka should be destroyed D. Town Dhaka is polluted E. Some towns in Bangladesh should be destroyed
A BDE
B BAE
C ADE
D CDB
Each question consists of five statements following by options consisting of three statements put together in a specific order. Choose the option which indicates a valid argument, that is, where the third statement is a conclusion drawn from the preceding two statements. A.Some towns in Bangladesh are polluted .B.All polluted towns should be destroyed.C.Town Dhaka should be destroyed.D.Town Dhaka is polluted.E.Some towns in Bangladesh should be destroyed
A BDE
B BAE
C ADE
D CDB
The amount of chemical coagulant added for treatment of polluted water __________ with increase in temperature of the polluted water to be treated.
A Decreases
B Increases
C Remains constant
D May increase or decrease ; depends on the chemical characteristics of polluted water
Coal mines drainage waste water (acidic in nature) results from the earth's water percolating through the voids created in coal bed during mining. This polluted water which either drains out naturally to water courses or are removed before starting the mining is
A Neutralised by alkali treatment
B Left as such without any treatment
C Diluted with fresh water to reduce its acidity
D None of these
In order to protect the aquatic creatures, the dissolved oxygen content in fresh water stream should never be less than __________ PPm.
A 0.5
B 1
C 5
D 20
Presence of non-biodegradable substances, like alkyl benzene sulphonate (ABS) from the detergents in polluted water stream causes
A Fire hazards
B Explosion hazards
C Persistent foam
D Depletion of dissolved oxygen
Radioactive substances present in the polluted water stream can be removed by
A Biological oxygen treatment
B Coagulation and filtration
C Adsorption in ion exchange materials
D None of these
Which of the following is the most efficient for removal of very finely divided suspended solids and colloidal matter from the polluted water stream?
A Sedimentation tank
B Circular clarifier
C Mechanical flocculation
D Chemical coagulation
Waste/polluted water discharged from electroplating, blast furnace and coal mining industries contain mainly __________ substances.
A Radioactive
B Organic
C Inorganic
D None of these
A man takes twice as long to row a distance against the stream as to row the same distance in favor of the stream . The ratio of the speed of the boat (in still water ) and the stream is :
A 2 : 1
B 3 : 2
C 4 : 3
D 3: 1

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