71. 


(a) 3.84 days

(b) 3.14 days

(c) 2.84 days

(d) 2.14 days

Answer: (b)

72. Consider following operating data for conventional activated sludge treatment plant: MLSS = MLVSS


F/M (Food/ Micro-organism) ratio will be:

(a) 0.215 kg BOD/day/kg of MLSS

(b) 0.335 kg BOD/day/kg of MLSS

(c) 0.455 kg BOD/day/kg of MLSS

(d) 0.575 kg BOD/day/kg of MLSS

Answer: (a)

73. Which one of the following groups represents secondary air pollutants?

(a) Ozone, Formaldehyde, Peroxy-acetyl-nitrate, and Halogen compounds

(b) Formaldehyde, Hydrocarbon, Ozone and Photochemical smog

(c) Ozone, Acid mist, Formaldehyde and Photochemical smog

(d) Formaldehyde, Acid mists, Hydrocarbon and Photochemical smog

Answer: (c)

74. Consider the following statements with reference to stability of atmosphere:

1. Air stability is dependent directly on the environmental lapse rate

2. If environmental lapse rate is less than the adiabatic lapse rate, stability occurs

Which of the above statements is/are correct?

(a) 1 only

(b) 2 only

(c) Both 1 and 2

(d) Neither 1nor 2

Answer: (c)

75. The mass specific gravity of a fully saturated specimen of clay having a water content of 36% is 1.86. On oven drying, the mass specific gravity drops to 1.72. The specific gravity of clay will be:

(a) 1.42

(b) 1.89

(c) 2.24

(d) 2.69

Answer: (d)

76. The porosity of a soil sample is 35 % and the specific gravity of soil particles is 2.7. The submerged unit weight of the soil will be nearly:


Answer: (b)

77. 

Answer: (c)

78. Consider the following results regarding a lateral pressure in a triaxial compression test on a cohesive soil:


The lateral pressure will be nearly:


Answer: (d)

79. Due to a rise of temperature, the viscosity and unit weight of the percolating fluid are reduced to 75 % and 97 % respectively. Other things being constant, the percentage change in coefficient of permeability will be:

(a) 26.5 %

(b) 29.5 %

(c) 33.5 %

(d) 37.5 %

Answer: (b)

80. The intensity of vertical pressure at a point 4 𝑚 directly below a 20 kN point load acting at a horizontal ground surface will be nearly:


Answer: (c)