Internal Structure of Earth - Practice Test 4

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

1. Q1.P-waves are also known as:

   • A.Transverse waves
   • B.Longitudinal / Compressional waves✓ Correct Answer
   • C.Surface waves
   • D.Light waves

   Explanation: P-waves push and pull the rock (compressional).

2. Q2.S-waves are also known as:

   • A.Longitudinal waves
   • B.Transverse / Shear waves✓ Correct Answer
   • C.Sound waves
   • D.Primary waves

   Explanation: S-waves move particles perpendicular to propagation (transverse).

3. Q3.The crust forms the outer skin of the Earth similar to the skin of an:

   • A.Apple✓ Correct Answer
   • B.Orange
   • C.Egg
   • D.Onion

   Explanation: Analogy: The crust is thin relative to the whole Earth, like an apple's skin.

4. Q4.Who provided the classical model of Earth's layers (Sial, Sima, Nife)?

   • A.Edward Suess✓ Correct Answer
   • B.Wegener
   • C.Holmes
   • D.Davis

   Explanation: Edward Suess proposed the chemical layering of Sial, Sima, and Nife.

5. Q5.Which element makes the core magnetic?

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

   Explanation: Iron is ferromagnetic and generates the magnetic field.

6. Q6.Continental Drift theory relies on the concept that:

   • A.Sima floats on Sial
   • B.Sial floats on Sima✓ Correct Answer
   • C.Core floats on Mantle
   • D.Crust is static

   Explanation: Wegener suggested lighter Sial continents float on the denser Sima ocean floor (though Plate Tectonics updated this).

7. Q7.The temperature gradient is higher in:

   • A.Crust✓ Correct Answer
   • B.Mantle
   • C.Core
   • D.Atmosphere

   Explanation: Temperature increases rapidly in the crust compared to the deep interior.

8. Q8.Which state of matter allows P-waves to pass?

   • A.Solid only
   • B.Liquid only
   • C.Solid, Liquid, and Gas✓ Correct Answer
   • D.Gas only

   Explanation: P-waves can travel through all states of matter.

9. Q9.The bulk of the Earth's mass is in the:

   • A.Crust
   • B.Mantle✓ Correct Answer
   • C.Core
   • D.Atmosphere

   Explanation: The Mantle contains the most mass (approx 67-68%).

10. Q10.The inner core has a radius of about:

    • A.1220 km✓ Correct Answer
    • B.3500 km
    • C.6371 km
    • D.500 km

    Explanation: The solid inner core has a radius of roughly 1,220 km.

11. Q11.What separates the upper mantle from the lower mantle?

    • A.Repetti Discontinuity✓ Correct Answer
    • B.Conrad Discontinuity
    • C.Moho
    • D.Gutenberg

    Explanation: Repetti discontinuity is the transition zone within the mantle.

12. Q12.The oceanic crust is youngest at:

    • A.Mid-Ocean Ridges✓ Correct Answer
    • B.Trenches
    • C.Continental Margins
    • D.Abyssal Plains

    Explanation: New crust is formed at mid-ocean ridges due to seafloor spreading.

13. Q13.Which instrument helps determining the epicenter of an earthquake?

    • A.Seismograph data from 3 stations✓ Correct Answer
    • B.Barometer
    • C.Radar
    • D.Sonar

    Explanation: Triangulation using data from at least three seismographs locates the epicenter.

14. Q14.The point vertically above the focus on the surface is called:

    • A.Epicenter✓ Correct Answer
    • B.Hypocenter
    • C.Fault
    • D.Crater

    Explanation: The Epicenter is directly above the earthquake's focus (hypocenter).

15. Q15.Earth's magnetic field protects us from:

    • A.Solar Winds / Radiation✓ Correct Answer
    • B.Rain
    • C.Meteorites
    • D.Tides

    Explanation: The magnetosphere deflects harmful solar particles.

16. Q16.The layer 'Nife' is associated with:

    • A.Core✓ Correct Answer
    • B.Mantle
    • C.Crust
    • D.Atmosphere

    Explanation: Nife (Ni + Fe) is the composition of the Core.

17. Q17.Who coined the term 'Lithosphere'?

    • A.Joseph Barrell✓ Correct Answer
    • B.Wegener
    • C.Suess
    • D.Daly

    Explanation: Joseph Barrell introduced the concept of the lithosphere and asthenosphere.

18. Q18.The temperature of the inner core is higher than the melting point of iron, yet it is solid because:

    • A.Pressure is extremely high✓ Correct Answer
    • B.It is made of rock
    • C.It is frozen
    • D.Gravity is low

    Explanation: Pressure raises the melting point, keeping iron solid.

19. Q19.Which crust is denser?

    • A.Oceanic✓ Correct Answer
    • B.Continental
    • C.Both are same
    • D.None

    Explanation: Oceanic crust (basaltic) is denser than continental crust.

20. Q20.The transition zone of the Earth is called:

    • A.Mantle Transition Zone (410-660 km)✓ Correct Answer
    • B.Crust
    • C.Core
    • D.Surface

    Explanation: The region between upper and lower mantle involves phase changes in minerals.