Rocks & Minerals – NDA Geography PYQs

Question 1 [NDA 2006-I]
Match List-I (Type of Rocks) with List-II (Example):
A. Igneous Rocks — 1. Basalt and Granite
B. Metamorphic Rocks — 2. Limestone and Sandstone
C. Sedimentary Rocks — 3. Marble and Quartzite

(a) A-1, B-2, C-3
(b) A-1, B-3, C-2
(c) A-2, B-3, C-1
(d) A-3, B-1, C-2

Answer: (b) A-1, B-3, C-2
Igneous rocks include basalt (extrusive) and granite (intrusive) — formed from cooled magma. Metamorphic rocks include marble (from limestone) and quartzite (from sandstone) — formed by heat and pressure. Sedimentary rocks include limestone and sandstone — formed from deposited sediments.

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Question 2 [NDA 2006-II]
Sandstone is a:
(a) Extrusive igneous rock
(b) Intrusive igneous rock
(c) Metamorphic rock
(d) Sedimentary rock

Answer: (d) Sedimentary rock
Sandstone is formed from sand grains that have been deposited in layers and cemented together over time. It is a mechanically (clastically) formed sedimentary rock. Under heat and pressure, sandstone transforms into quartzite — a metamorphic rock.

Question 3 [NDA 2008-I]
Consider the following statements:

1. Coal is a sedimentary rock.
2. Basalt is an igneous rock.

Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2

Answer: (c) Both 1 and 2
Coal forms from the remains of ancient forests compressed over millions of years — it is an organically formed sedimentary rock. Basalt forms from lava that cools rapidly at the surface — it is an extrusive igneous rock. Both statements are correct.

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Question 4 [NDA 2010-I]
Which one of the following is generally found in sedimentary rocks?
(a) Basalt
(b) Silica
(c) Shale
(d) Magnesium

Answer: (c) Shale
Shale is the most common sedimentary rock — formed from fine clay particles deposited in calm water and compressed over time. Basalt is igneous. Silica is a mineral component found in many rocks. Magnesium is a chemical element. Shale is the only complete rock type in the options.

Question 5 [NDA 2010-II]
Consider the following statements about rocks:
I. Shale becomes slate through metamorphosis.
II. Shale is converted to slate when it is subjected to tremendous pressure and high temperature.

Which of the statements given above is/are correct?
(a) I only
(b) II only
(c) Both I and II
(d) Neither I nor II

Answer: (c) Both I and II
Both statements are correct. Shale is a sedimentary rock made of clay particles. When subjected to heat and pressure during mountain building or deep burial, it transforms into slate — a metamorphic rock. The two statements say the same thing in different ways — both are true.

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Question 6 [NDA 2011-II]
Which one among the following is a primary rock?
(a) Sedimentary
(b) Igneous
(c) Metamorphic
(d) None of the above

Answer: (b) Igneous
Igneous rocks are called primary rocks because they form directly from magma — the original molten material of the early Earth. All other rock types — sedimentary and metamorphic — derive ultimately from igneous rocks through various transformation processes.

Question 7 [NDA 2012-II]
Which one among the following rocks does NOT belong to the same group?
(a) Shale
(b) Limestone
(c) Slate
(d) Sandstone

Answer: (c) Slate
Shale, limestone, and sandstone are all sedimentary rocks. Slate is a metamorphic rock — it forms when shale is subjected to heat and pressure. Slate does not belong to the sedimentary group.

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Question 8 [NDA 2013-I]
Radioactive decay provides an internal source of heat for the Earth. This helps in the formation of which type of rocks?
(a) Igneous
(b) Sedimentary
(c) Metamorphic
(d) All of the above

Answer: (a) Igneous
Radioactive decay in the mantle generates heat that keeps rock molten. This molten material (magma) rises and cools to form igneous rocks. Sedimentary and metamorphic rocks form through entirely different processes that are not directly driven by radioactive heat.

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Question 9 [NDA 2014-I]
What is the correct sequence from the smallest to the largest grain of the following types of clastic rocks?
(a) Shale, sandstone, conglomerate, siltstone
(b) Shale, siltstone, sandstone, conglomerate
(c) Conglomerate, sandstone, shale, siltstone
(d) Sandstone, siltstone, conglomerate, shale

Answer: (b) Shale, siltstone, sandstone, conglomerate
Shale has the finest grains (clay-sized). Siltstone has slightly coarser grains. Sandstone has sand-sized grains. Conglomerate has the largest — pebble and gravel sized fragments. This sequence from finest to coarsest is a classic exam question.

Question 10 [NDA 2014-II]
Quartzite is metamorphosed from:
(a) Limestone
(b) Plutonic rock
(c) Sandstone
(d) Shale

Answer: (c) Sandstone
Sandstone, when subjected to intense heat and pressure, transforms into quartzite — a very hard, dense metamorphic rock highly resistant to erosion. Limestone becomes marble. Shale becomes slate. These parent-metamorphic pairs are the most important facts in this chapter.

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Question 11 [NDA 2017-II]
Which one of the following is NOT an igneous rock?
(a) Gabbro
(b) Granite
(c) Dolomite
(d) Basalt

Answer: (c) Dolomite
Dolomite is a sedimentary or metamorphic rock — it is definitely not igneous. Granite, basalt, and gabbro are all igneous rocks. Gabbro is the coarse-grained intrusive equivalent of basalt.

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Question 12 [NDA 2018-II]
Which one of the following is NOT an agent of metamorphism?
(a) Heat
(b) Compression
(c) Decomposition
(d) Solution

Answer: (c) Decomposition
Decomposition is a process of biological or chemical weathering at the Earth’s surface — it breaks rocks down, not transforms them through metamorphism. Heat, compression (pressure), and chemical solutions are all agents of metamorphism.

Question 13 [NDA 2019-II]
Which one of the following sedimentary rocks is organically formed?
(a) Shale
(b) Chert
(c) Halite
(d) Chalk

Answer: (d) Chalk
Chalk is made from the microscopic shells and skeletons of tiny marine organisms (foraminifera) that accumulated on the sea floor over millions of years. Shale is mechanically formed (clay particles). Halite (rock salt) is chemically formed (evaporation of seawater). Chert is also chemically formed (from silica).

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Question 14 [NDA 2020-I]
Chalk and marble are different forms of:
(a) Calcium hydrogen carbonate
(b) Calcium carbonate
(c) Calcium acetate
(d) Sodium carbonate

Answer: (b) Calcium carbonate
Both chalk (sedimentary) and marble (metamorphic) are made of calcium carbonate (CaCO₃). The difference is that marble has been recrystallised under heat and pressure, making it harder and more uniform. Chalk is soft and crumbly; marble is hard and smooth.

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Question 15 [NDA 2023-I]
Which one of the following is NOT an igneous rock?
(a) Granite
(b) Slate
(c) Basalt
(d) Gabbro

Answer: (b) Slate
Slate is a metamorphic rock — formed when shale (sedimentary) is compressed and heated. Granite, basalt, and gabbro are all igneous rocks. Granite is intrusive (cooled slowly underground). Basalt and gabbro are related — basalt is extrusive and fine-grained; gabbro is intrusive and coarse-grained.

Question 16 [NDA 2024-II]
Which one of the following is an example of both an igneous as well as a metamorphic rock?
(a) Gabbro
(b) Geyserite
(c) Gneissoid
(d) Granite

Answer: (d) Granite
Granite originates as an intrusive igneous rock formed from slowly cooled magma. Under extreme heat and pressure deep in the Earth, it can transform into gneiss — a metamorphic rock. Because granite is the parent of gneiss, it sits at the boundary of both categories in some classifications.

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Question 17 [NDA 2024-II]
Which one of the following is correct?
(a) Pyroxene is commonly found in meteorites
(b) Amphiboles form about 20% of the Earth’s crust
(c) Quartz is soluble in water
(d) The word sedimentary is derived from the Latin word kelimentum

Answer: (a) Pyroxene is commonly found in meteorites
Pyroxene is indeed found in meteorites — it is one of the most common minerals in stony meteorites. Amphiboles do not form 20% of the crust. Quartz is not soluble in ordinary water — it is one of the most resistant minerals. The word sedimentary comes from the Latin sedimentum meaning settling.

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Question 18 [NDA 2025-I]
Which of the following is the correct ascending order of the given minerals in terms of their presence in the Earth’s crust?

1. Amphibolite
2. Mica
3. Pyroxene

(a) 2, 3, 1
(b) 1, 2, 3
(c) 2, 1, 3
(d) 1, 3, 2

Answer: (a) 2, 3, 1
In ascending order of abundance in the Earth’s crust: Mica (least common among these three) → Pyroxene → Amphibolite (most common among these three).

Question 19 [NDA 2025-I]
Which one of the following is formed when volcanic ash is carried by running water and is deposited as a sedimentary layer?
(a) Basalt
(b) Lapilli
(c) Slate
(d) Tuff

Answer: (d) Tuff
Tuff is formed when volcanic ash is transported by water and deposited in layers like a sedimentary rock. It is different from basalt (which forms from lava flows) and lapilli (which are volcanic fragments thrown directly from the volcano). Slate is a metamorphic rock with no connection to volcanic ash.

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