The most suitable chemical which can be applied to the water surface for reducing evaporation is________________?

Related Mcqs:

1. Under the same conditions, which of the following shapes of water surface will give the highest rate of evaporation ?

   A. flat water surface
   B. convex water surface
   C. concave water surface
   D. independent of shape of water surface

2. Rate of evaporation from a water surface increases if_________________?

   1) difference of vapour pressure between water and air is increased
   2) velocity of wind is decreased
   3) concentration of soluble solids in water is decreased
   The correct answer is?

   A. (1) and (i2)
   B. (2) and (3)
   C. (2) and (3)
   D. (1), (2) and (3)

3. The stage of river carrying a discharge of Q m7sec at a point is 10 m and slope of water surface is (1/4000). The discharge of a flood at the same point and same stage of 10 m with a water surface slope of(l/1000) will be________________?

   A. V2 Q m3/sec
   B. 0.5 Q mVsec
   C. 2 Q m3/sec
   D. 4 Q m3/sec

4. When surface of transpiration is submerged under water, then potential evapotranspiration is________________?

   A. much more than evapotranspiration
   B. much less than evapotranspiration
   C. equal to evapotranspiration
   D. equal to or less than evapotranspi-ration

5. In case of non-availability of space due to topography, the most suitable spillway is________________?

   A. straight drop spillway
   B. shaft spillway
   C. chute spillway
   D. ogee spillway

6. When the upstream face of a gravity dam is vertical, then the intensity of water pressure at the water surface and at the base respectively will be_______________?

   A. 0 and wH212
   B. wH2/2and wH2/3
   C. wH and 0
   D. OandwII

   where w is unit weight of water and H is the depth of water

7. The total capacity of a reservoir is 25 million cubic metres and dead storage is 5 million cubic metres. If the average volume of sediment deposition is 0.10 million cubic metre per year, then the usefulness of the reservoir will start reducing after_________________?

   A. 50 years
   B. 150 years
   C. 200 years
   D. 250 years

8. The ratio of average values of shear stresses produced on the bed and the banks of a channel due to flowing water is________________?

   A. less than 1
   B. equal to 1
   C. greater than 1
   D. equal to zero

9. Main purpose of mean water training for rivers is________________?

   A. flood control
   B. to provide sufficient depth of water in navigable channels, during low water periods
   C. to preserve the channel in good shape by efficient disposal of suspended and bed load
   D. all of the above

10. The most suitable material for the central impervious core of a zoned embankment type dam is_______________?

    A. clay
    B. coarse sand
    C. silty clay
    D. clay mixed with fine sand