106. The quantity of water retained by the sub-soil against gravity, is known

A. yield

B. porosity

C. specific yield

D. specific retention

107. If the grain size of soil increases

A. surface area decreases

B. specific retention decreases

C. specific yield increases

D. all the above.

108. Pick up the incorrect statement from the following :

A. The rate of flow of water through a unit cross-sectional area under a unit hydraulic gradient, is called coefficient of permeability

B. The rate of flow of water through a vertical strip of the acquifer of unit width and full depth under a unit hydraulic gradient, is called coefficient of transmissibility

C. The flow of water through acquifers, is governed by the Darcy's law

D. The term 'transmissibility' was introduced by Meinzer

109. With the usual meanings of letters, the equation V = Di4ia 4001 s used for determining the velocity of ground water flow in metres per day. It is known as

A. Meinzer's formula

B. Slichter's formula

C. Darcy's formula

D. Hazen's formula.

110. The equation V - 1000 /Di? x (1.8 T + 42) which is used 60 for determining the velocity of ground water flow in metres per day is known as

A. Meinzer's formula

B. Slichter's formula

C. Darcy's formula

D. Hazen formula.

111. If the viscosity of ground water is 1.00, the Slitcher's constant is 400, the effective size of soil particles in acquifer is 0.5 mm and hydraulic gradient is 1 in 80, the velocity of flow is

A. 0.25 m/day

B. 0.50 m/day

C. 0.75 m/day

D. 1.25 m/day.

112. Pick up the correct statement from the following :

A. A confined bed of impervious material laid over an acquifer, is known as an aqui-clude

B. The top most water bearing strata having no acquifer, is known as non-artesion acquifer

C. The ordinary gravity wells which supply water from the top most water bearing strata, are called water table wells

D. All the above.

Page **16** of **21**