Thermodynamics - Advanced topics in Geology - Geology & Geophysics Previous Year Questions

1

2008 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2008

The number of components in the system is

A

4

B

3

C

2

D

1

Open complete paper

2

2008 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2008

The degree of freedom of the mineral assemblage in P-T space is

A

1

B

2

C

3

D

4

Open complete paper

3

2012 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2012

Calculate the degree(s) of freedom of the assemblage orthopyroxene + clinopyroxene + plagioclase + hornblende + quartz + fluid in the chemical system CaO–FeO–MgO–Al₂O₃–SiO₂–H₂O with pressure and temperature as physical variables.

A

0

B

1

C

2

D

3

Open complete paper

4

2012 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2012

Choose the correct statement?

A

Solvus occurs in both P and Q

B

Solvus is absent in both P and Q

C

Solvus occurs in P but not in Q

D

Solvus occurs in Q but not in P

Open complete paper

5

2013 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2013

If a radioactive isotope has a decay constant of \(1.55 \times 10^{-10}\) year\(^{-1}\), its half-life (in years) would be

A

\(4.57 \times 10^9\)

B

\(4.47 \times 10^9\)

C

\(4.57 \times 10^{10}\)

D

\(4.47 \times 10^{10}\)

Open complete paper

6

2014 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2014

A phase-diagram with a specified bulk-composition is known as

A

isograd diagram

B

AFM diagram

C

pseudosection

D

ACF diagram

Open complete paper

7

2014 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2014

The standard free energy change (in kJ) at 25°C of the dissolution of anhydrite at equilibrium in the equation CaSO₄ ⇌ Ca²⁺ + SO₄²⁻, given K=3.4 × 10⁻⁵ and R=8.314 J/mol/K, is

A

43.7

B

37.4

C

30.2

D

25.5

Open complete paper

8

2016 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2016

The ΔG° of a reaction \(2 Fe_3O_4 + 0.5 O_2 = 3 Fe_2O_3\) at 300°C and 500 bars is -40.657 kilo calories. The value of the logarithm of oxygen (log \(f_{O_2}\)) at that temperature and pressure is __________.

Check answer

Open complete paper

9

2022 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2022

The following reaction occurs at 1 bar and 823 K.
Grossular + Quartz = Anorthite + 2 Wollastonite

Mineral	Entropy (\(S^{1,823}\)) kJ \(K^{-1}\)	Volume (\(V^{1,823}\)) J \(bar^{-1}\)
Grossular	0.255	12.535
Quartz	0.042	2.269
Anorthite	0.200	10.079
Wollastonite	0.082	3.993

Using the above molar thermodynamic data, the calculated slope of the above reaction is _____ bar \(K^{-1}\). [round off to 2 decimal places]

Check answer

Open complete paper

10

2022 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2022

The radioactive isotopes \(^A X\) and \(^B X\) of an element X at the time of formation of a rock sample were in equal proportions. Subsequently, in a closed system, it was found that the abundances of the isotopes were in the ratio \(^B X / ^A X = 128.55\). The elapsed time since the formation of the sample is _________ years. [round off to 1 decimal place] [Assume: decay rate of \(\lambda_A = 9.85 \times 10^{-3}\) y⁻¹, \(\lambda_B = 1.55 \times 10^{-3}\) y⁻¹].

Check answer

Open complete paper

11

2025 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2025 [Session 1]

In the isochemical phase diagram shown below, the curved arrow represents the P-T path. The variance at peak metamorphism is _____

Chemical System:
K₂O-FeO-MgO-Al₂O₃-SiO₂-H₂O-TiO₂-Fe₂O₃

a Grt-Sil-Kfs-Pt-Qz-Liq      Garnet = Grt
b Grt-Sil-Crd-Kfs-Pl-Qz-Liq    Sillimanite = Sil
c Grt-Sil-Kfs-Crd-Pl-Qz        Cordierite = Crd
d Grt-Kfs-Crd-Pl-Qz                K-feldspar = Kfs
e Grt-Kfs-Crd-Pl-Qz-Liq          Plagioclase = Pl
f Grt-Crd-Pl-Qz-Liq                  Quartz = Qz
g Grt-Crd-Pl-Qz-Liq                  Melt = Liq
h Grt-Crd-Qz-Liq
i Grt-Sil-Crd-Pl-Qz-Liq
j Grt-Sil-Crd-Kfs-Qz-Liq
k Grt-Sil-Crd-Qz-Liq
l Grt-Sil-Kfs-Qz-Liq
m Grt-Sil-Qz-Liq

(Answer in integer)

Check answer

Open complete paper

12

2025 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2025 [Session 1]

²³⁰Th and ²²⁶Ra are intermediate nuclides in the decay series of ²³⁸U to ²⁰⁶Pb. The half-lives of ²³⁸U, ²³⁰Th, and ²²⁶Ra are 4.47 billion years, 75,000 years, and 1600 years, respectively. At secular equilibrium, when activities are equal, 10 billion atoms of ²³⁸U are present. The number of atoms of ²²⁶Ra present at equilibrium is _____
(Answer in integer)

Check answer

Open complete paper

13

2017 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2017

The standard thermodynamic data for enstatite (Mg₂Si₂O₆), quartz (SiO₂) and forsterite (Mg₂SiO₄) is given in the table below. The Gibb’s free energy of the reaction Mg₂SiO₄ + SiO₂ = Mg₂Si₂O₆ at 600 K and 1 bar is ________ J. (Assume Cₚ = 0 for all minerals in the reaction)

Check answer

Open complete paper

14

2018 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2018

The stability field boundary between two minerals A and B is linear with a positive slope in P-T space. The molar entropy of A and B are 85.5 and 92.5 Joules K⁻¹, respectively and their respective molar volumes are 35.5 and 38.2 cc. The slope of the phase boundary in P-T space is ________ bar K⁻¹.

Check answer

Open complete paper

15

2018 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2018

Five moles of gas A (volume V1) and 3 moles of gas B (volume V2) were kept in separate containers. These two gases are completely transferred to a new container of volume V. Assuming isothermal condition, and that the work done is only mechanical, the entropy change of the system is ________ Joules K⁻¹. (R = 8.3 J K⁻¹ mole⁻¹)

Check answer

Open complete paper

16

2019 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2019

\(^{87}\)Rb decays to \(^{87}\)Sr with a decay constant λ = 1.42 × 10⁻¹¹ per year. If at the time of formation, a system contains 8 × 10¹⁰ atoms of \(^{87}\)Rb and 10⁹ atoms of \(^{87}\)Sr, the number of \(^{87}\)Sr atoms in this system at the end of 4 half-lives will be ________ × 10⁹. Assume close system evolution for parent-daughter pair.

Check answer

Open complete paper

17

2020 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2020

Nuclide A decays to nuclide B exclusively through α and β decay, such that the mass number is reduced by 32 and the atomic number is reduced by 10. The number of β particles emitted during the decay of nuclide A to nuclide B is ______.

Check answer

Open complete paper

18

2020 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2020

The figure below represents an isobaric binary liquidus phase diagram, with the solid phases A, B and C. What are the degrees of freedom associated with equilibrium phase assemblages represented by the bulk compositions w, x, y and z, in the fields indicated in the figure?

A

w = 2, x = 1, y = 1, z = 1

B

w = 2, x = 1, y = 0, z = 2

C

w = 1, x = 1, y = 0, z = 1

D

w = 1, x = 1, y = 1, z = 2

Open complete paper

19

2023 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology & Geophysics (GG) 2023 [Session 1]

Given ΔVᵣ and ΔSᵣ are the volume and entropy of reaction, respectively, the most suitable conditions for the reaction to be used as a geothermometer are

A

small ΔVᵣ but large ΔSᵣ

B

small ΔSᵣ but large ΔVᵣ

C

positive ΔVᵣ but negative ΔSᵣ

D

negative ΔVᵣ but positive ΔSᵣ

Open complete paper

20

2026 · Geology & Geophysics · Advanced topics in Geology · Thermodynamics

Geology and Geophysics - Geology (GG) 2026

For a chemical system with 5 phases at the invariant point, the number of possible univariant reactions in pressure-temperature space is ____ (answer in integer).

Check answer

Open complete paper