Related Questions

For existence of aquatic life in water, the dissolved oxygen content in it, should not be less than __________ ppm.
A 10000
B 5
C 500
D 1000
Dissolved oxygen content in river water is around __________ ppm.
A 5
B 100
C 250
D 500
The minimum dissolved oxygen which should always be present in water in order to save the aquatic life is
A 1 ppm
B 4 ppm
C 10 ppm
D 40 ppm
The ratio of quantity of water in fresh fruit to that of dry fruits is 7 : 2 . If 400 km of dry fruits contain 50 km of water then find the weight of the water in same fruits when they were fresh?
A 100 km
B 150 km
C 175 kg
D 125 kg
Replenishment of dissolved oxygen in water stream polluted with industrial waste occurs by
A Natural aeration of water stream
B Photosynthetic action of algae
C Both A & B
D Neither A nor B
Presence of __________ in water stream are deleterious to aquatic life.
A Soluble and toxic organics
B Suspended solids
C Heavy metals and cynides
D All of the above
Fresh fruit contains 68% water and dry fruit contains 20% water, How much dry fruit can be obtained from 100 km of fresh fruits?
A 20 kg
B 30 kg
C 35 kg
D 40 kg
Fresh grapes contain 90% water by weight while dried grapes contain 20% water by weight. What is the weight of dry grapes available from 20 kg of fresh grapes?
A 2 kg
B 2.4 kg
C 2.5 kg
D None of these
Fresh grapes contain 80 percent water while dry grapes contain 10 percent water. If the weight of the dry grapes is 250 kg what is total weight when it was fresh? 
A 1000 kg
B 1100 kg
C 1125 kg
D 1225 kg
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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