Rocks - Practice Test 2

Attempt the quiz above first, then review every question with its correct answer and a short explanation below.

1. Q1.Rocks formed by the cooling of magma deep inside the earth are called:

   • A.Plutonic rocks✓ Correct Answer
   • B.Volcanic rocks
   • C.Sedimentary rocks
   • D.Fossils

   Explanation: Intrusive igneous rocks formed at depth are called Plutonic rocks.

2. Q2.Basaltic rocks are usually associated with:

   • A.Volcanic eruptions✓ Correct Answer
   • B.River deposition
   • C.Wind erosion
   • D.Glacial movement

   Explanation: Basalt is a volcanic rock formed from lava flow.

3. Q3.Which of these is a chemical sedimentary rock?

   • A.Sandstone
   • B.Limestone / Gypsum✓ Correct Answer
   • C.Granite
   • D.Slate

   Explanation: Gypsum and rock salt (and some limestone) precipitate chemically from water.

4. Q4.Which of these is an organic sedimentary rock?

   • A.Coal✓ Correct Answer
   • B.Sandstone
   • C.Basalt
   • D.Quartzite

   Explanation: Coal forms from the accumulation of plant material (organic matter).

5. Q5.Stratification (layers) is a characteristic of:

   • A.Igneous rocks
   • B.Sedimentary rocks✓ Correct Answer
   • C.Metamorphic rocks
   • D.Volcanic rocks

   Explanation: Sedimentary rocks are often stratified, deposited in layers (strata).

6. Q6.Which mineral is the hardest naturally occurring substance?

   • A.Quartz
   • B.Diamond✓ Correct Answer
   • C.Topaz
   • D.Corundum

   Explanation: Diamond is the hardest natural mineral (Mohs hardness 10).

7. Q7.Which is the softest mineral on Mohs scale?

   • A.Talc✓ Correct Answer
   • B.Gypsum
   • C.Calcite
   • D.Diamond

   Explanation: Talc is the softest mineral (Mohs hardness 1).

8. Q8.The continuous process of transformation of rocks from one form to another is called:

   • A.Rock Cycle✓ Correct Answer
   • B.Water Cycle
   • C.Carbon Cycle
   • D.Life Cycle

   Explanation: The Rock Cycle describes how rocks change between igneous, sedimentary, and metamorphic forms.

9. Q9.Granite is rich in:

   • A.Silica and Magnesium
   • B.Silica and Aluminum (Feldspar/Quartz)✓ Correct Answer
   • C.Iron and Nickel
   • D.Calcium and Carbon

   Explanation: Granite is a felsic rock rich in silica (quartz) and aluminum (feldspar).

10. Q10.Basalt is rich in:

    • A.Iron and Magnesium✓ Correct Answer
    • B.Silica and Aluminum
    • C.Potassium
    • D.Sodium

    Explanation: Basalt is a mafic rock rich in magnesium and iron.

11. Q11.Conglomerate is a type of:

    • A.Igneous rock
    • B.Sedimentary rock✓ Correct Answer
    • C.Metamorphic rock
    • D.Mineral

    Explanation: Conglomerate is a sedimentary rock made of rounded pebbles.

12. Q12.Obsidian is an example of:

    • A.Intrusive Igneous
    • B.Extrusive Igneous (Volcanic glass)✓ Correct Answer
    • C.Sedimentary
    • D.Metamorphic

    Explanation: Obsidian is volcanic glass formed by rapid cooling of lava.

13. Q13.Which rock typically has a layered structure called Foliation?

    • A.Igneous
    • B.Metamorphic✓ Correct Answer
    • C.Sedimentary
    • D.None

    Explanation: Foliation (alignment of minerals) is a key feature of many metamorphic rocks like gneiss and schist.

14. Q14.Petroleum (Crude Oil) is found in which rocks?

    • A.Igneous
    • B.Metamorphic
    • C.Sedimentary✓ Correct Answer
    • D.Volcanic

    Explanation: Petroleum is trapped in porous sedimentary rocks like sandstone and limestone.

15. Q15.Which of these is a Metamorphic rock used for roofing and blackboards?

    • A.Slate✓ Correct Answer
    • B.Marble
    • C.Quartzite
    • D.Gneiss

    Explanation: Slate splits easily into thin sheets, making it useful for roofs and boards.

16. Q16.The Deccan Plateau is primarily made of:

    • A.Granite
    • B.Basalt✓ Correct Answer
    • C.Sandstone
    • D.Limestone

    Explanation: The Deccan Traps are huge flood basalt provinces.

17. Q17.Lithification is the process associated with:

    • A.Igneous rocks
    • B.Sedimentary rocks✓ Correct Answer
    • C.Metamorphic rocks
    • D.Magma

    Explanation: Lithification turns loose sediments into solid sedimentary rock.

18. Q18.Batholiths, Laccoliths, and Dykes are landforms associated with:

    • A.Intrusive Igneous activity✓ Correct Answer
    • B.Sedimentary deposition
    • C.Metamorphism
    • D.Glacial erosion

    Explanation: These are structures formed by magma cooling underground (intrusive).

19. Q19.Which of the following is NOT a mineral?

    • A.Quartz
    • B.Feldspar
    • C.Mica
    • D.Granite✓ Correct Answer

    Explanation: Granite is a rock composed of minerals (quartz, feldspar, mica), not a mineral itself.

20. Q20.Which rock type contains crystals?

    • A.Intrusive Igneous✓ Correct Answer
    • B.Extrusive Igneous (Glassy)
    • C.Sedimentary (Clastic)
    • D.All

    Explanation: Intrusive rocks cool slowly, allowing large crystals to form.