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Plate Tectonics: Boundaries, Earthquakes and Mountains — MCQs with Answers

Test what you know about Plate Tectonics: Boundaries, Earthquakes and Mountains with 10 UPSC Prelims-style questions. Try each one first, then tap “Show answer” for the correct option and its explanation.

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  • 10 practice questions
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  1. Q1. Consider the following statements: 1. A tectonic plate includes crust and rigid uppermost mantle. 2. One plate can carry both continental and oceanic areas. Which of the statements given above is/are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Show answer

    Correct answer: (C) Both 1 and 2

    Explanation

    Correct Answer: (C). Both statements correctly describe lithospheric plates. A plate is not restricted to the crust, and it is not synonymous with a continent. Continental and oceanic areas can belong to one moving unit. Options A and B omit a correct statement, while D incorrectly rejects both.

  2. Q2. Which statement best describes the asthenosphere in relation to plate tectonics?

    1. It is mechanically weaker mantle material that can deform over geological time.
    2. It is a completely liquid ocean occupying the entire mantle.
    3. It is another name for continental crust.
    4. It is the rigid layer above the lithosphere.
    Show answer

    Correct answer: (A) It is mechanically weaker mantle material that can deform over geological time.

    Explanation

    Correct Answer: (A). The asthenosphere lies below the lithosphere and is mechanically weaker. Predominantly solid mantle rock can deform and flow over long geological periods. B incorrectly makes the entire mantle liquid. C confuses it with crust, while D reverses its position and gives it the rigidity associated with the lithosphere.

  3. Q3. Consider the following pairs: 1. Divergent boundary — Plates move apart 2. Convergent boundary — Plates approach each other 3. Transform boundary — Plates move apart to create new ocean floor How many pairs are correctly matched?

    1. Only one
    2. Only two
    3. All three
    4. None
    Show answer

    Correct answer: (B) Only two

    Explanation

    Correct Answer: (B). The first two pairs correctly identify relative movement. The third incorrectly assigns spreading to a transform boundary, where the characteristic motion is lateral sliding. New ocean floor at a spreading centre belongs to divergence. Exactly two pairs are therefore correct; the other counts include or exclude a pair incorrectly.

  4. Q4. Which conclusion about a continental rift follows from the article?

    1. It must already be a fully developed ocean basin.
    2. It necessarily indicates lateral transform movement.
    3. It marks the consumption of oceanic lithosphere in every case.
    4. It can represent continental extension without being a completed ocean basin.
    Show answer

    Correct answer: (D) It can represent continental extension without being a completed ocean basin.

    Explanation

    Correct Answer: (D). A continental rift records extension and faulting; it should not automatically be called a completed ocean basin. A confuses a developing process with its possible later result. B substitutes transform sliding for extension, and C substitutes subduction. D preserves the distinction between ongoing rifting and an established ocean basin.

  5. Q5. Which process helps generate magma above a subducting slab?

    1. Fluids released from the slab promote partial melting in the overlying mantle.
    2. The entire descending plate must melt solely because of friction.
    3. Lateral sliding creates new ocean floor at every transform boundary.
    4. Continental coastlines necessarily become volcanic arcs.
    Show answer

    Correct answer: (A) Fluids released from the slab promote partial melting in the overlying mantle.

    Explanation

    Correct Answer: (A). Fluids from the descending slab can promote partial melting in the mantle above it, allowing magma to rise. B wrongly reduces the mechanism to complete frictional melting of the slab. C misdescribes transform motion, while D assumes coastlines and tectonic volcanic settings must coincide. A identifies the relevant mechanism.

  6. Q6. Consider the following statements about the Himalayas: 1. They illustrate continental collision between India and Eurasia. 2. Their central explanation is identical to that of a typical oceanic subduction volcanic arc. Which statements are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Show answer

    Correct answer: (A) 1 only

    Explanation

    Correct Answer: (A). Statement 1 is correct: India–Eurasia continental collision explains the Himalayan setting. Statement 2 is incorrect because shortening, folding and thickening of continental crust differ from the typical volcanic-arc explanation. B accepts only the wrong statement, C accepts both, and D rejects the correct identification of continental collision.

  7. Q7. Why is a transform boundary sometimes called conservative?

    1. It cannot produce damaging earthquakes.
    2. Its characteristic motion does not systematically create or consume crust.
    3. It always preserves the chemical composition of every rock.
    4. It converts every fault into an ocean trench.
    Show answer

    Correct answer: (B) Its characteristic motion does not systematically create or consume crust.

    Explanation

    Correct Answer: (B). Conservative describes the crustal balance associated with lateral sliding, not safety or chemical preservation. A is wrong because transform boundaries can produce damaging shallow earthquakes. C gives the term an unrelated chemical meaning. D confuses transform faulting with subduction trenches. B correctly connects the term with crust creation and consumption.

  8. Q8. Assertion: Slow plate movement can be associated with sudden earthquake shaking. Reason: A locked fault can store elastic strain energy that is released during sudden slip. Select the correct answer.

    1. The Assertion is correct, but the Reason is incorrect.
    2. The Assertion is incorrect, but the Reason is correct.
    3. Both are correct, and the Reason explains the Assertion.
    4. Both are correct, but the Reason does not explain the Assertion.
    Show answer

    Correct answer: (C) Both are correct, and the Reason explains the Assertion.

    Explanation

    Correct Answer: (C). Both statements are correct. Gradual deformation can accumulate while a fault remains locked; sudden slip then releases stored energy as seismic waves. This directly explains why slow plate motion and sudden shaking are compatible. A and B reject a true statement, while D misses the explanatory connection between them.

  9. Q9. Consider the following statements: 1. Every earthquake occurs at a plate boundary. 2. Distance from the nearest mapped plate boundary is sufficient to declare a location earthquake-free. Which statements are correct?

    1. 1 only
    2. 2 only
    3. Both 1 and 2
    4. Neither 1 nor 2
    Show answer

    Correct answer: (D) Neither 1 nor 2

    Explanation

    Correct Answer: (D). Both statements turn a broad pattern into an incorrect absolute rule. Most earthquakes occur near plate boundaries, but intraplate earthquakes also occur, including along older weaknesses. Consequently, distance alone cannot establish absence of earthquakes. A, B and C each accept at least one unsupported absolute claim; D rejects both.

  10. Q10. Which sequence is most useful for interpreting a plate-boundary landform?

    1. Identify coastline, assume a plate edge, then assign volcanism.
    2. Identify relative motion, lithosphere type, then compatible landforms.
    3. Identify a mountain, assume subduction, then ignore the material involved.
    4. Identify a fault, assume a continent, then predict an exact earthquake date.
    Show answer

    Correct answer: (B) Identify relative motion, lithosphere type, then compatible landforms.

    Explanation

    Correct Answer: (B). The article recommends moving from relative motion to lithosphere type and then to features consistent with both. A wrongly equates coastlines with boundaries. C ignores the distinction between collision and subduction. D confuses structural scales and adds an unsupported prediction. B preserves the causal reasoning needed to interpret a landform.

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