Question No 1
1. The clay mineral primarily governing the swelling behavior of black cotton soil is [GATE, 2014] (A) halloysite (B) illite (C) kaolinite (D) montmorillonite
Ans : Montomorillonite mineral exhibits the swelling behavior in black cotton soils. Hence, the correct answer is option (D).
Question No 2
2. An earth embankment is to be constructed with compacted cohesionless soil. The volume of the embankment is 5000 m3 and the target dry unit weight is 16.2 kN/m3. Three nearby sites (see the given figure) have been identified from where the required soil can be transported to the construction site. The void ratios (e) of different sites are shown in the figure. Answer the specific gravity of soil to be 2.7 for all three sites. If the cost of transportation per km is twice the cost of excavation per m3 of borrow pits, which site would you choose as the most economic solution? (Use unit weight of water = 10 kN/m3) [GATE, 2015]
(A) Site X (B) Site Y (C) Site Z (D) Any of the sites
Question No 3
3. The relationship between porosity (η), specific yield (S y) and specific retention (Sx) of an unconfined aquifer is [GATE, 2015]
(A) S y + Sx = η
(B) S y + η = Sx
(C) Sx + η = S y
(D) S y + Sx + η = 1
Porosity = Specific yield + Specific retention η = Sy + Sr
Hence, the correct answer is option (A).