81. The major natural source of Fluoride (F) in water is:

(a) Amphiboles

(b) Gypsum

(c) Limestone

(d) Dolomite

Answer: (a)

82. Defluoridation of waters can be made by using:

(a) Aluminium phosphate

(b) Aluminium chloride

(c) Sodium chloride

(d) Sodium nitrate

Answer: (b)

83. Piper’s trilinear diagram comprises of two lower triangular fields and a central diamond-shaped field. All the three fields have scales reading in:

(a) 200 parts

(b) 150 parts

(c) 100 parts

(d) 50 parts

Answer: (c)

84. The commonly used dye to trace the groundwater pollution is:

(a) Rhodamine

(b) Serrtia Marcescens

(c) Fluouresine

(d) Chlorine

Answer: (c)

85. Methemoglobinemia is caused due to excess of:

(a) Fluoride

(b) Nitrate

(c) Chloride

(d) Sulphate

Answer: (b)

86. Which of the following guidelines are correct to minimize the risk of collapse of a building during an expected shock?

1. Foundations for concrete and masonry buildings should be excavated to the same level throughout the building

2. Parapets, cantilevers, arches and domes should be avoided as for as possible

3. Continuity of cross walls should be maintained as for as possible

(a) 1 and 2 only

(b) 1, 2 and 3

(c) 1 and 3 only

(d) 2 and 3 only

Answer: (b)

87. A seismic surface wave causing the ground to shake in an elliptical motion with no transverse or perpendicular motion is called:

(a) P-wave

(b) Rayleigh wave

(c) S-wave

(d) SH-wave

Answer: (b)

88. Which of the following statements are correct regarding Love waves?

1. When the angle of reflection at the base of the soil layer is more than the critical angle, SH waves are trapped in the soil layer

2. The particle motion is in horizontal plane transverse to the direction of the wave propagation

3. Love ways are not dispersive in nature

(a) 1, 2 and 3

(b) 1 and 2 only

(c) 1 and 3 only

(d) 2 and 3 only

Answer: (b)

89. Which volcanic eruption was the terrestrial source of great tsunami?

(a) Cascadia Subduction zone

(b) Krakatoa volcano between Java and Sumatra

(c) Volcano of Okushiri Island and Hokkaido

(d) Eruption of Mount Saint Helens

Answer: (b)

90. Which of the following statements are correct?

1. In strike-slip faulting, the directivity pulse occurs on the strike-normal component and fling step occurs on the strike-parallel component

2. In dip-slip faulting the fling step and directivity pulse occur on the strike-normal component

3. In dip-slip faulting the fling step and directivity pulse occur on the strike-parallel component

(a) 1, 2 and 3

(b) 2 and 3 only

(c) 1 and 3 only

(d) 1 and 2 only

Answer: (d)