Which of the following statements is correct?

The hydraulic head that would produce a quick condition in a sand stratum of thickness 1.5 m, specific gravity 2.67 and voids ratio 0.67 is equal to

A. 1.0m

B. 1.5m

C. 2.0m

D. 3m

Clay layer A with single drainage and coefficient of consolidation Cv takes 6 months to achieve 50% consolidation. The time taken by clay layer B of the same thickness with double drainage and coefficient of consolidation $$\frac{{{\text{Cv}}}}{2}$$ to achieve the same degree of consolidation is

A. 3 months

B. 6 months

C. 12 months

D. 24 months

Degree of consolidation is

A. directly proportional to time and inversely proportional to drainage path

B. directly proportional to time and inversely proportional to square of drainage path

C. directly proportional to drainage path and inversely proportional to time

D. directly proportional to square of drainage path and inversely proportional to time

Select the correct range of density index, 1_D

A. 1_D > 0

B. 1_D ≥ 0

C. 0 < 1_D < 1

D. 0 ≤ 1_D ≤ 1