October 2023

Q. Which one is CORRECT for the following equilibrium reaction between quartz and magnetite: Ans: Option D

Q. Which one of the following ore minerals shows internal reflection? (A) Orpiment             (B) Magnetite            (C) Pyrite                   (D) Molybdenite Ans: Orpiment

Q. Which one of the following Himalayan lithounits predates India-Eurasia collision? (A) Kasauli sandstone                                  (B) Rangit Pebble Slate (C) Annapurna granite                                  (D) Lower Karewa sandstone Ans: Rangit Pebble Slate

Q. If the total porosity of a soil is 20%, its void ratio (%) is Ans: 25-25

Q. Given that the velocity of P-waves in a sandstone matrix is 5600 m/s and that in oil is 1200 m/s, the velocity of P-wave propagation in oil saturated sandstone with 30% porosity is__________m/s. (Use Wyllie time average equation.) Ans: 2660-2670

Q. Assume a flat earth with crustal thickness of 35 km and average crustal and upper mantle P-wave velocities of 6.4 km.s–1 and 8.1 km.s–1, respectively. The minimum distance from the epicenter of a near surface earthquake at which Pn-waves are observed is__________km. Ans: 85-85

Q. The unit of shear modulus (rigidity modulus) is (A) kg m-1s-2             (B) m2 s-2                   (C) kg m-2 s-2             (D) m-1 Ans: kg m-1s-2    

Q. A ‘gentle’ fold with an interlimb angle equal to 160° appears tight (apparent interlimb angle equal to 20°) in horizontal section. According to the plunge of the fold axis, it can also be classified as (A) horizontal fold.                                      (B) gently plunging fold. (C) steeply plunging fold.                            (D) vertical fold. Ans: gently plunging fold.

Q, The geoid can be best defined as A. an oblate spheroid that best approximates the shape of the earth. B. a surface over which the value of gravity is constant. C. the physical surface of the earth. D. an equipotential surface of gravity of the earth. Ans: an equipotential surface of gravity of the

Q, The maximum and the minimum principal stresses are denoted by σ1 and σ3, respectively. The differential stress can have an absolute value greater than σ1 when A. σ1 and σ3 are both compressive. B. σ1 is compressive and σ3 is tensile. C. σ1 and σ3 are equal. D. σ1 and σ3 are both tensile.