Rocks & Their Types MCQs with Answers
Solved Rocks & Their Types MCQs with answers — sedimentary, metamorphic, igneous (intrusive & extrusive) rocks & hydrosphere. Free quiz + PDF for PPSC, FPSC, NTS, CSS & PMS.
Rocks & Their Types — Master Reference for Pakistani Competitive Exams
The chapter Rocks & Their Types is a high-frequency Everyday Science / Geology / Geography topic in Pakistan’s PPSC, FPSC, NTS, CSS, PMS, OTS, CTS, BPSC, KPPSC and SPSC One Paper exams. Almost every Junior Clerk, Tehsildar, Assistant, Sub-Inspector, Lecturer and BPS-14 to BPS-17 paper carries 2–3 MCQs from this chapter — and it is core content for the CSS Screening MPT (General Science & Ability) paper. This page consolidates solved MCQs with answers covering all three main rock types: sedimentary (sandstone, limestone, shale, coal, breccia, conglomerate, dolomites, chert), metamorphic (marble, slate, gneiss, quartzite, amphibolite, soapstone), igneous (intrusive/plutonic — granite, diorite, peridotite, pegmatite; extrusive/volcanic — basalt, andesite, obsidian, dacite, tuff) — plus the hydrosphere (ocean currents, Kuroshio, Benguela, salinity, monsoon winds, spring tide, glaciers). For wider context, see Wikipedia: Rock (geology) and the USGS Mineral Resources Program — the most authoritative geology references.
Three Main Types of Rocks — Quick Comparison
| Type | Formation | Examples |
|---|---|---|
| Sedimentary | Formed at or near Earth’s surface by accumulation & lithification of sediment, or precipitation from solution. | Sandstone, limestone, shale, coal, breccia, chert, conglomerate, dolomites, gypsum, siltstone, coquina. |
| Metamorphic | Formed when rocks are subjected to high heat, high pressure, or hot mineral-rich fluids. | Marble, slate, gneiss, quartzite, amphibolite, blue schist, eclogite, soapstone. |
| Igneous (magmatic) | Formed when magma (molten rock) cools and crystallises. | Granite, basalt, andesite, dacite, obsidian, diorite, peridotite, pegmatite, tuff. |
Igneous Rocks — Intrusive vs Extrusive
| Group | Also Called | Where It Forms | Examples |
|---|---|---|---|
| Intrusive | Plutonic rocks | Within Earth’s crust — magma rises, fills voids, hardens underground. | Granite, diorite, peridotite, pegmatite, diabase. |
| Extrusive | Volcanic rocks | On Earth’s surface — magma reaches surface as lava, cools rapidly. | Basalt, andesite, dacite, obsidian, tuff. |
Key Facts to Memorise
- Sedimentary rocks make up most of the rocks on Earth — and Earth’s crust below the oceans is composed of sedimentary rocks.
- Artesian wells are found in sedimentary rocks.
- Coal is an organic sedimentary rock that forms mainly from plant debris.
- Marble is NOT a sedimentary rock — it is a metamorphic rock (metamorphosed limestone).
- Amphibolite is a coarse-grained metamorphic rock composed of green/brown/black amphibole minerals and plagioclase feldspar.
- Soapstone is a metamorphic rock; basalts form by the solidification of lava.
- Igneous rocks are also known as magmatic rocks.
- Intrusive igneous rocks = plutonic rocks (form inside Earth’s crust).
- Extrusive igneous rocks = volcanic rocks (form when lava cools on the surface).
- Hydrosphere — A discontinuous layer of water at or near Earth’s surface (liquid + frozen + groundwater + atmospheric vapour).
- Water is the most abundant substance at the surface of Earth.
- ~1.4 billion km³ of water (liquid + frozen) makes up oceans, lakes, streams, glaciers and groundwater.
- Kuroshio Current — Warm north-easterly ocean current off the coast of Japan.
- Benguela Current — Eastern boundary current of the South Atlantic.
- Monsoon winds in the northern hemisphere reverse: NE in winter → SW in summer.
- Northern Indian Ocean currents change direction TWICE A YEAR due to NE & SW monsoon winds.
- Average ocean salinity — Approximately 3.5% (34–35 parts per thousand).
- Spring tide — The tide at its maximum height.
- Glacier — A huge mass of ice that moves slowly over land.
- Ocean horizontal water movement — Driven mainly by density difference.
Exam tip: Lock six anchors and you cover ~80% of all MCQs from this chapter — 3 rock types (Sedimentary / Metamorphic / Igneous), Marble = metamorphic, NOT sedimentary, Igneous = magmatic; Intrusive = plutonic; Extrusive = volcanic, Coal = organic sedimentary, Ocean salinity = 3.5%, and Spring tide = maximum height.
Frequently Asked Questions
(1) Sedimentary — formed by accumulation and lithification of sediment near Earth’s surface (sandstone, limestone, shale, coal); (2) Metamorphic — formed when rocks face high heat, pressure or hot fluids (marble, slate, gneiss, quartzite); (3) Igneous — formed when magma cools and crystallises (granite, basalt, obsidian).
Intrusive (or plutonic) rocks form inside Earth’s crust as magma cools slowly — examples: granite, diorite, peridotite. Extrusive (or volcanic) rocks form on Earth’s surface when lava cools quickly — examples: basalt, andesite, obsidian, tuff.
Sedimentary rocks make up most of the rocks on Earth — and Earth’s crust below the oceans is composed of sedimentary rocks.
No. Marble is a metamorphic rock — it forms when limestone (a sedimentary rock) is subjected to high heat and pressure.
On average, seawater in the world’s oceans has a salinity of approximately 3.5% — equivalent to 34–35 parts per thousand.
A glacier is a huge mass of ice that moves slowly over land.
Yes — essential. Rocks & Their Types MCQs are tested in every One Paper, NTS NAT, GAT, OTS, CTS, BPSC, KPPSC, SPSC, PPSC and FPSC exam, and form core CSS Screening MPT (General Science & Ability) content. Expect 2–3 MCQs per 100-mark paper.
Yes. Click the Download PDF button to get all Rocks & Their Types MCQs with correct answers as a branded QuizWing PDF for offline revision.