GATE GG-1 topic:geochemistry PYQs & Answers

Questions 1–10 of 37. Imported answers require independent review unless marked reviewed.

Consider that the upper continental crust is 10 km thick and made up of granitic rock having density of 2800 kg/m³. The surface heat flow due to radiogenic heat from the granitic rock having heat production value of 10⁻⁹ W/kg is____________ mW/m² (answer in integer).

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Choose the CORRECT factor(s) from the following, which affect(s) the

isotopic ratio in foraminifera growing in an ocean.

Your answerSelect all correct options. You can choose more than one.

Temperature

Oxygen isotopic composition of water

Growth of continental ice sheets

Continental detritus input

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If the atomic mass unit of ⁸⁵Rb and ⁸⁷Rb are 84.912 and 86.901, respectively, then the abundance of ⁸⁷Rb is __________ % (rounded off to nearest integer).

[Use: Average atomic mass of Rb = 85.467 amu]

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A hydrothermal solution contains dissolved ions of Ca²⁺ and SO₄²⁻. If the Saturation Index (SI) of the solution is negative, which of the following statements is/are CORRECT if gypsum is added to the solution?

Your answerSelect all correct options. You can choose more than one.

Gypsum will precipitate from the solution

Gypsum will dissolve in the solution

The concentration of Ca²⁺ will increase and SO₄²⁻ will decrease in the solution

The concentrations of both Ca²⁺ and SO₄²⁻ will increase in the solution

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A sample contains 7 wt% CaO and 5 wt% MgO. The molar ratio of CaO to MgO in the sample is __________

(Round off to two decimal places)

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Which one of the following statements explains why elements Li, Be, and B have low cosmic abundance?

Your answerChoose one option.

These elements have low masses and hence, they break apart easily

These elements have low binding energies which makes them unstable at high temperatures at the core of stars

The low abundance of these elements is a unique feature of big stars with mass greater than 10 times that of our Sun

These elements are highly reactive and hence, unstable

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Shown below is a schematic plot of

(deviation of

in a sample relative to CHUR) versus time. The two solid lines represent the evolution curves for the depleted mantle reservoir and the continental crust. Which one of the four dashed lines, marked 1, 2, 3, and 4, represents the evolution of the CHUR?

Diagram for Geology and Geophysics question 30

Your answerChoose one option.

Line 1

Line 2

Line 3

Line 4

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Compared to Fe, Mg, and Ca, the content of K is extremely low in igneous clinopyroxene. Which of the following CANNOT explain its low abundance?

Your answerSelect all correct options. You can choose more than one.

K⁺ has a larger ionic radius than Fe²⁺, Mg²⁺ and Ca²⁺

K is incompatible and hence, enriched in the continental crust

K is fluid mobile and hence, easily leached out of clinopyroxene

K has multiple oxidation states

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In a hypothetical rock, the K

values of element E in minerals M1, M2, and M3 are 1.5, 1.0, and 0.5, respectively. The modal abundances of M1, M2, and M3 are 10%, 40%, and 50%, respectively. The bulk partition coefficient of element E in this rock is __________

(Round off to two decimal places)

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A particular Index of Alteration (IA) is defined as the molar concentration ratio (expressed as weight percentage) of fluid immobile element(s) to fluid mobile element(s) and is expressed by 100 × ([Al

] / ). For chemical weathering of silicate rocks, which one of the following statements is correct?

Your answerChoose one option.

High IA values (> 85) indicate intense chemical weathering

Low IA values (< 15) indicate intense chemical weathering

The IA values do not vary for silicate rocks

The minimum IA value for an unweathered granite is 0

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GATE GG-1 topic:geochemistry PYQs

How to practice topic:geochemistry

Question 26

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