Geo-Science Success Best Institution for GATE (PSUs), CSIR-NET UPSC-GSI, IFS, IIT(JAM), BHU Ent. in Geology & Geophysics

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1 GATE Online Test: 1 (General Geology) Duration: 2 hours Maximum Marks: 100 Read the following instructions carefully 1: There are total of 65 questions carrying 100 marks. 2: This question paper consists of 2 parts. The 2 parts are: 3: Part-A, consists of 30 questions each of 1-mark & Part-B, consist of 35 questions of 2-mark. 5: All questions that are not attempted will result in zero marks. However, wrong answers for multiple choice type questions (MCQ) will result in NEGATIVE marks. For all MCQ questions a wrong answer will result in deduction of ⅓ marks for a 1-mark question and ⅔ marks for a 2- mark question. There is NO NEGATIVE MARKING for questions of NUMERICAL ANSWER TYPE. 6: Your answers shall be updated and saved on a server periodically and also at the end of the examination. The examination will stop automatically at the end of 120 minutes. PART-A 1) The furthest points of a planetary orbit around the Planet is called (a) Aphelion (b) Perihelion (c) Apogee (d) Perigee 2) The density of planet is second highest in solar system. (a) Earth (b) Venus (c) Mercury (d) Mars 3) The planet which contributes maximum to the angular momentum of the solar system is (a) Earth (c) Mars (b) Saturn (d) Jupiter

2 4) Which is the smallest satellite? (a) Deimos (c) Titan (b) Phobos (d) Triton 5) The diameter of Earth along the pole..(km) (a) (b) 6356 (c) 6371 (d) ) Where do S wave shadow zone lies? (in degree) (a) (b) (c) (d) ) The pair of curves that depicts the radioactive decay and growth of a parent-daughter pair in the following figure is: (a) P, Q (b) P, R (c) P, S (d) S, Q

3 8) An elevated land mass attaining isostatic compensation a) is always uplifted b) always undergoes subsidence c) is uplifted in the case of over compensation and undergoes subsidence otherwise d) undergoes subsidence in the case of over compensation and is uplifted otherwise 9) The magnitude of an earthquake is determined from a) the epicentral distance and focal depth b) arrival times of seismic waves at the observatories c) magnitude of destruction to life and property d) amplitude of horizontal ground motion 10) Percentage of total gaseous mass of the atmosphere contained in the troposphere is (a) 30% (b) 60% (c) 75% (d) 90% 11) In a solid mixture of two end-member-phases A & B such that A is 60% and B is 40%. If another phase C is added to this to make 20% of this solid, then the concentration of A & B in this solid would be, respectively (a) 60%, 40% (b) 48%, 32% (c) 52%, 28% (d) 45%, 35% 12) Magma is generated in subduction zone because of (a) decrease in melting point of a part of mantle due to decrease in pressure (b) decrease in melting point due to influx of fluid in the mantle (c) decrease in melting point of a part of mantle due to convergence of plates (d) fractional heating of the mantle 13) Elevated land masses undergoing isostatic compensation are associated with (a) Strong positive Bouguer anomalies irrespective of level of compensation (b) Strong negative Bouguer anomalies irrespective of level of compensation (c) Strong positive Bouguer anomalies in case of under compensation and negative otherwise (d) Strong negative Bouguer anomalies in case of under compensation and positive otherwise

4 14) Away from the epicentre of an Earthquake, its (a) intensity and magnitude remain the same (b) intensity remain the same, but the magnitude decreases (c) magnitude remains the same, but intensity decreases (d) intensity and magnitude decreases 15) If V1, V2 & V3 are the velocities of longitudinal waves in the lower mantle, outer core & inner core of the Earth, respectively, then (a) V1>V2>V3 (b) V1>V3>V2 (c) V2>V3>V1 (d) V3>V2>V1 16) Considering the Airy isostatic compensation for a mountain having elevation of km above the mean sea level at a point P, if the thickness of its root below P is 9km.(Consider densities of crustal rock and upper mantle as 2.7gm/cc and 3.3gm/cc respectively). (a) 18km (b) 16km (c) 2km (d) 4km 17) Out of the following gases which one has the highest contribution towards the greenhouse effect on the Earth? (A) CO2 (B) CO (C) CH4 (D) H2O Ans: D 18) Radio-wave absorbing layer present in (a) Troposphere (c) Mesosphere (b) stratosphere (d) ionosphere

5 19) Which of the following is a non radioactive isotope of lead? (a) Pb204 (c) Pb207 (b) Pb206 (d) Pb208 20) The radial extent of the core is: (a) 2886 km (c) 3486 km (b) 4113 km (d) 1227 km 21) According to the doctrine of Isostasy, a region of lower density shows: i) Negative anomaly iii) Mass excess ii) Mass deficiency iv) Positive anomally (a) i only (c) ii only (b) i and iii only (d) ii and iv only 22) After decaying through 7 half-life periods, the original amount of radioactive substance that reduces to an amount of 1/64 g, is (A) 0.25 g (B) 0.50 g (C) 1.0 g (D) 2.0 g Ans: D 23) If a radioactive isotope has a decay constant of year -1, its half-life (in years) would be (A) (B) (C) (D) Ans: B

6 24) Which of the following is a non radioactive isotope of lead? (a) Pb204 (c) Pb207 (b) Pb206 (d) Pb208 25) ln the plate tectonic theory, the "ring of fire" around the Pacific ocean is related to (A) convergent plate boundary (B) divergent plate boundary (C) hot spots (D) transform fault Ans: A 26) Which of the following is located closest to the Ninety-East Ridge? (a) Bombay High (b) Lakshwadweep Island (c) Andaman and Nicobar Islands (d) Maldives 27) In paleomagnetism, detrital magnetization is an important process for study of (a) Sedimentary rocks (b) metamorphic rocks (c) basic igneous rocks (d) acidic igneous rocks 28) The boundary between the Indian and Eurasian plates is the (a) Maim central thrust (b) Main Boundary thrust

7 (c) South Tibetan Detachment zone (d) Indus-Tsangpo Suture Zone 29) Which type of sedimentary basin is formed close to continent-continent collisional settings? (a) Fore-arc basin (b) Peripheral foreland basin (c) back-arc basin (d) Retro-arc foreland basin 30) What rock would you expect to find at the base of a typical oceanic plate? (a) Basalt (b) Diorite (c) Gabbro (d) Peridotite

8 Part-B 31) At what depth all mineral change into perovskite and minor Fe-Mg oxide? (a) 440 km (b) 660 km (c) 200 km (d) 800km 32) Which one of the following mineral assemblages, found in mantle nodules, represents the greatest depth of derivation? (a) Plagioclase+ Clinopyroxene (b) Clinopyroxene+Olivine (c) Olivine+Spinel (d) Olivine+Garnet 33) Name the discontinuity where seismic wave (Vp) changes from 6.7 km/s to 8.1 km/s, Also velocity of S-wave changes from. to km (a) Conrad & 3 to 4 (b) Moho & 3.5 to 4.5 (c) Moho & 3.9 to 4.7 (d) Gutenberg & 3.5 to ) Assuming the Planet Earth to be a perfect sphere, its equatorial velocity is approximately km/hr. (a) 1668 (b) 2000 (c) 1768 (d) ) In order to have the same value of the surface acceleration due to gravity as on Earth, a planet twice its radius must have a mean relative density of a) 2.75 b) 5.5 c) 1.4 d) 2.25

9 36) Two planets A and B of masses M and 4M orbit around their central star at distances d and 4d respectively. Compared to A, the planet B orbits around the star a) twice slower. b) four times slower. c) eight times slower. d) sixteen times slower. 37) A planet is identical to the Earth in all respects except that its atmospheric composition is purely oxygen (instead of Earth s 80:20 mixture of nitrogen and oxygen). The scale height of such an atmosphere relative to that of the Earth is expected to be a) (7.2/8) b) (8/7.2) c) 1 d) (32/28) 38) Which of the following isotope ratios get significantly fractionated during evaporation of sea water? a) 87Sr/86Sr b) 16O/18O c) 143Nd/144Nd d) 12C/13C 39) The densities of the Earth and Mars are in the ratio 14:10. The rate of decrease of the gravity field of Mars on its surface with elevation would be: (a) 0.31 gal/km (b) 0.25 gal/km (c) 0.22 gal/km (d) 0.10 gal/km 40) A radiogenic isotope has half-life of 1 hour and we have atoms of that particular isotope in a particular system at a particular time. How much atoms of that isotope will be there after 6 hours? (A) 78 (B) 156 (C) 313 (D) 625 Ans: B

10 41) A basaltic lava flow is found to have a 87 Sr/ 86 Sr ratio of O.720, and a 87 Rb/ 86 Sr ratio of If the initial 87 Sr/ 86 Sr value is determined to be 0.704, what is the age of the flow? ( Assume λ = 1.42 x year). (A) 2.5 x 10 9 years (B) 1.5 x 10 9 years (C) 2.5 x 10 6 years (D) 1.5 x 10 6 years Ans: B 42) Determine the correctness or otherwise of the following Assertion (a) and Reason (r). Assertion: Strontium concentration in a basic magma decreases with fractional crystallization of plagioclase. Reason: Strontium is a compatible trace element in plagioclase during magmatic crystallization. (A) Both (a) and (r) are true and (r) is the correct reason for (a) (B) (a) is true but (r) is false (C) (a) is false but (r) is true (D) Both (a) and (r) are true but (r) is not the correct reason for (a) 43) A cubic wooden block of densities 0.8gm/cc when floats in water have an exposure of 2cm above the water level. The side of the cube is (a) 10cm (b) 18cm (c) 6cm (d) 4cm 44) If the Sun were to lose some mass, then the duration of an year on the Earth would be (a) longer, with the length of the day being the same (b) shorter, with the length of the day being the same (c) of the same length, the length of the day being larger (d) of the same length, the length of the day being shorter 45) If the average density of rocks in the crust is 2750 kg/m 3, then what is the value of lithostatic stress at a depth of 35km in the crust? (a) MPa (b) MPa (c) MPa (d) MPa

11 46) In a borehole, the formation fluids at a depth of 2500m have a density of 1.09gm/cm. The measured formation pressure at that depth is 350kg/cm 2. Then the overpressure at that depth is a) 350 kg/cm 2 b) 77.5 kg/cm 2 c) kg/cm 2 d) kg/cm 2 47) A 30 km continental crust of density 2.5 gm/ccis in isostatic equlibirium, when it overlies the mantle of density 3.5gm/cc. A 10 km thick oceanic crust of density 3.0gm/cc under ocean is also in isostatic equlibirium, with refrence to the continental crust. The thickness of the water column in the oceans is (a) 5 km (b) 8 km (c) 10 km (d) 12 km 48) The scattering efficiency of a particle in the Rayleigh regime for radiation of wavelength x is 16 times that for the wavelength of y the relationship between wavelengths x & y is: (a) x=4y (b) x=1/4y (c) x=8y (d) x=16y 49) An active trench is present in the vicinity of (a) Andaman & Nicobar Islands (b) Gulf of Cambay (c) Lakshadweep (d) Krishna-Godavari Delta 50) Mid-Oceanic ridges mark plate margins and can be traced by belts of focus earthquakes. (a) constructive, shalow (b) destructive, shalow (c) constructive, deep

12 (d) destructive, deep 51) For earthquakes of magnitude 6 & 7, the seismic wave amplitudes are A 6 and A 8 and the radiated energies are E 6 & E 8 respectively. Which one of the following is true? (a) A 8 10A 6 and E 8 32E 6 (b) A 8 8/6A 6 and E 8 10E 6 (c) A 8 100A 6 and E E 6 (d) A 8 100A 6 and E 8 32E 6 52) Which one of the following sedimentary basins is related to extension? a) Foredeep b) half-graben c) piggyback d) fore-arc 53) Fore-arc and back-arc are respectively locales of a) Extensional and flexural basins b) Thermal and contraction basins c) Flexural basins and Extensional basins d) Extensional and thermal basins 54) The Hawaii, Japan and Andaman & Nicobar islands respectively represents: a) Oceanic island, MORB, Island Arc b) Back arc, Island Arc and MORB c) Oceanic Island, Island Arc and Island arc d) MORB, Back arc and Island Arc 55) Andean Mountains- Atlantic Ocean-San Andreas fault represents one of the following sequences of plate boundries: a) Constructive-Destructive-Conservative b) Destructive- Constructive- Conservative c) Conservative- Constructive- Destructive d) Conservative-Destructive- Constructive

13 56) The surface expression of the lothosphere descending into the asthenosphere is known as (a) Island arc (b) Trench (c) Benioff Zone (d) Canyon 57) Earthquakes with deep foci( 700km) are common in a) MORB b) Island Arcs c) Himalayan Mountain Belt d) Continental rifts 58) Which one of the following is not related to hotspots? a) Submarine plateaus b) Aseismic ridges c) Deccan traps d) Andaman Islands 59) An expedition across the mid-oceanic ridges mapped magnetic reversals and the width of basalts, which can be used to infer: a) Intensity of Earth s magnetic field b) Position of Earth s magnetic poles c) Magnetic latidudes of the region mapped d) Rate of sea-floor spreading 60) Which one of the following is not a plate boundary? a) Carlsberg Ridge b) South East Indian Ridge c) East Pacific Rise d) Ninety East Ridge

14 61) Compared to the normal crust, an isostatically undercompensated land mass has a a) Thinner crust and undergoes upliftment. b) Thinner crust and undergoes subsidence. c) Thicker crust and undergoes upliftment. d) Thicker crust and undergoes subsidence 62) In the case of earthquakes, isoseismal maps are prepared for their a) magnitude b) energy c) intensity d) Frequency 63) S waves move faster through gabbro than granodiorite because a) gabbro is denser than granodiorite but has much higher shear modulus b) granodiorite is denser than gabbro but has much higher shear modulus c) granodiorite is lighter than gabbro but has higher shear modulus d) granodiorite and gabbro have similar densities, but gabbro has higher shear modulus 64) Which one of the following cannot be related to the end of subduction and initiation of continent-continent collision? a) End of island-arc magmatism b) End of marine sedimentation c) Drastic decrease in the relative plate velocity d) Increase in the rate of erosion and weather- ing at the convergent boundary 65) A 2.0 km thick, and isostatically uncompensated, elevated land mass of density 2.7 g/cc is associated with a 14.0 km root at the crust-mantle boundary, where the mantle is denser by 0.3 g/cc than the lower crust. What would be the thickness of the root, when the land mass is isostatically compensated? a) 18.0 km b) 16.2 km c) 14.4 km d) 13.6 km

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