Some important MCQs related to 12th Geology Exam with Explanations -4

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Unit 1: General Geology

1. Which of the following is an example of a convergent plate boundary feature?
a) Mid-ocean ridge
b) Mountain range
c) Rift valley
d) Oceanic trench
Answer: b) Mountain range
Explanation: Convergent plate boundaries occur where two plates collide, often leading to the formation of mountain ranges, such as the Himalayas.

2. Which of the following is NOT true about the lithosphere?
a) It includes the crust and uppermost part of the mantle
b) It is rigid and brittle
c) It is part of the Earth's outer shell
d) It is composed of molten rock
Answer: d) It is composed of molten rock
Explanation: The lithosphere is solid and rigid, made up of the Earth's crust and uppermost mantle, while molten rock is typically found in the asthenosphere beneath the lithosphere.


3. The process by which one tectonic plate is forced beneath another is called:
a) Divergence
b) Subduction
c) Convection
d) Compression
Answer: b) Subduction
Explanation: Subduction occurs at convergent boundaries where one tectonic plate is forced beneath another, leading to the formation of oceanic trenches and volcanic arcs.
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Unit 2: Petrology

4. Which of the following is an example of an intrusive igneous rock?
a) Pumice
b) Obsidian
c) Granite
d) Basalt
Answer: c) Granite
Explanation: Granite is an intrusive igneous rock that forms when magma cools slowly beneath the Earth's surface, allowing large crystals to form.


5. Which of the following describes the formation of marble?
a) Metamorphism of limestone
b) Sedimentation of calcium carbonate
c) Cooling of magma
d) Weathering of granite
Answer: a) Metamorphism of limestone
Explanation: Marble forms from the metamorphism of limestone under high pressure and temperature, resulting in a recrystallized rock.

6. Which of the following minerals is a primary component of granite?
a) Quartz
b) Feldspar
c) Mica
d) All of the above
Answer: d) All of the above
Explanation: Granite is composed mainly of quartz, feldspar, and mica, which are visible to the naked eye in this coarse-grained rock.
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Unit 3: Structural Geology

7. What is the characteristic feature of a syncline?
a) The youngest layers are in the center
b) The oldest layers are in the center
c) The rock layers dip away from the center
d) It is a faulted structure
Answer: a) The youngest layers are in the center
Explanation: A syncline is a fold in which the rock layers dip toward the center, and the youngest layers are found at the core of the fold.


8. A reverse fault is associated with which type of stress?
a) Compressional stress
b) Shear stress
c) Tensional stress
d) Radial stress
Answer: a) Compressional stress
Explanation: Reverse faults occur when compressional forces push the rock layers together, causing the hanging wall to move up relative to the footwall.


9. A fault in which two blocks of rock slide past each other horizontally is called a:
a) Strike-slip fault
b) Normal fault
c) Reverse fault
d) Thrust fault
Answer: a) Strike-slip fault
Explanation: In a strike-slip fault, rocks on either side of the fault move horizontally, typically due to shear stress.
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Unit 4: Paleontology

10. Which of the following fossil types provides evidence of past animal movement?
a) Mold
b) Cast
c) Footprint
d) Shell
Answer: c) Footprint
Explanation: Footprints are trace fossils that preserve evidence of an animal's movement and behavior, providing insight into ancient ecosystems.


11. Which period is known for the appearance of the first dinosaurs?
a) Cambrian
b) Triassic
c) Devonian
d) Jurassic
Answer: b) Triassic
Explanation: The first dinosaurs appeared during the Triassic period, which began around 250 million years ago.


12. The term "fossilization" refers to:
a) The process of an organism becoming a fossil
b) The age of a rock
c) The study of fossils
d) The burial of an organism by sediment
Answer: a) The process of an organism becoming a fossil
Explanation: Fossilization is the process through which organic material is preserved over time, typically through mineralization or other processes that occur after the organism's death.
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Unit 5: Economic Geology

13. Which mineral is the primary source of lead?
a) Galena
b) Pyrite
c) Sphalerite
d) Hematite
Answer: a) Galena
Explanation: Galena is the main ore of lead, containing lead sulfide (PbS) as its principal mineral component.


14. Which of the following is a significant use of gypsum?
a) Steel production
b) Cement manufacturing
c) Fuel production
d) Gold extraction
Answer: b) Cement manufacturing
Explanation: Gypsum is used in the production of cement as a setting regulator, helping to control the hardening process.


15. Which of the following is a non-renewable resource?
a) Solar energy
b) Wind energy
c) Coal
d) Geothermal energy
Answer: c) Coal
Explanation: Coal is a non-renewable fossil fuel that takes millions of years to form and is being depleted at a faster rate than it can be replenished.

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