Internal Structure of Earth - Practice Test 1

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

1. Q1.The study of the internal structure of the Earth is known as:

   • A.Geology✓ Correct Answer
   • B.Seismology
   • C.Cosmology
   • D.Meteorology

   Explanation: Geology is the primary field, while Seismology specifically uses seismic waves to infer internal structure.

2. Q2.Which source provides the most direct information about the Earth's interior?

   • A.Seismic waves
   • B.Volcanic eruptions✓ Correct Answer
   • C.Gravitational force
   • D.Earth's magnetism

   Explanation: Magma coming out from volcanoes gives direct evidence of the material inside the Earth.

3. Q3.The Earth is divided into how many main concentric layers?

   • A.2
   • B.3✓ Correct Answer
   • C.4
   • D.5

   Explanation: The three main layers are Crust, Mantle, and Core.

4. Q4.The outermost solid layer of the Earth is called:

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

   Explanation: The Crust is the thin, outermost solid shell of the Earth.

5. Q5.The term 'Sial' refers to which layer?

   • A.Continental Crust✓ Correct Answer
   • B.Oceanic Crust
   • C.Upper Mantle
   • D.Inner Core

   Explanation: Sial stands for Silica and Aluminum, which are dominant in the Continental Crust.

6. Q6.The term 'Sima' refers to which layer?

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

   Explanation: Sima stands for Silica and Magnesium, forming the Oceanic Crust.

7. Q7.The core of the Earth is also known as:

   • A.Sial
   • B.Sima
   • C.Nife✓ Correct Answer
   • D.Lithosphere

   Explanation: Nife stands for Nickel and Ferrous (Iron), the main components of the Core.

8. Q8.The boundary separating the Crust and the Mantle is called:

   • A.Gutenberg Discontinuity
   • B.Mohorovicic (Moho) Discontinuity✓ Correct Answer
   • C.Conrad Discontinuity
   • D.Lehmann Discontinuity

   Explanation: The Mohorovicic discontinuity (Moho) marks the boundary between the crust and the mantle.

9. Q9.The boundary separating the Mantle and the Core is called:

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

   Explanation: The Gutenberg discontinuity lies at a depth of about 2900 km between the mantle and core.

10. Q10.Which is the thickest layer of the Earth?

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

    Explanation: The Mantle constitutes about 84% of the Earth's volume and is approx 2900 km thick.

11. Q11.The inner core of the Earth is in which state?

    • A.Liquid
    • B.Solid✓ Correct Answer
    • C.Gas
    • D.Semi-solid

    Explanation: Due to immense pressure, the Inner Core remains solid despite high temperatures.

12. Q12.The outer core of the Earth is in which state?

    • A.Solid
    • B.Liquid✓ Correct Answer
    • C.Gas
    • D.Plasma

    Explanation: The Outer Core is in a liquid state, confirmed by the non-transmission of S-waves.

13. Q13.The Lithosphere comprises:

    • A.Crust only
    • B.Crust and upper solid Mantle✓ Correct Answer
    • C.Mantle and Core
    • D.Core only

    Explanation: The Lithosphere includes the Crust and the uppermost rigid part of the Mantle.

14. Q14.The Asthenosphere is located in:

    • A.Lower Crust
    • B.Upper Mantle✓ Correct Answer
    • C.Lower Mantle
    • D.Outer Core

    Explanation: The Asthenosphere is the semi-fluid layer in the upper mantle below the lithosphere.

15. Q15.The average density of the Earth is approximately:

    • A.2.7 g/cm³
    • B.5.5 g/cm³✓ Correct Answer
    • C.11 g/cm³
    • D.13 g/cm³

    Explanation: The average density of the Earth is 5.51 g/cm³.

16. Q16.Temperature inside the Earth increases with depth at an average rate of:

    • A.1°C for every 32 meters✓ Correct Answer
    • B.1°C for every 100 meters
    • C.1°C for every 1 km
    • D.10°C for every 32 meters

    Explanation: In the upper crust, temperature rises by approx 1°C for every 32 meters of depth.

17. Q17.Which element is the most abundant in the Earth's Crust?

    • A.Iron
    • B.Silicon
    • C.Oxygen✓ Correct Answer
    • D.Aluminum

    Explanation: Oxygen makes up about 46.6% of the Earth's crust by weight.

18. Q18.Which is the most abundant metal in the Earth's Crust?

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

    Explanation: Aluminum (~8%) is the most abundant metal in the crust.

19. Q19.As a whole, the Earth is composed mainly of which element?

    • A.Oxygen
    • B.Silicon
    • C.Iron✓ Correct Answer
    • D.Magnesium

    Explanation: Iron (~35%) is the most abundant element in the entire Earth (mostly in the core).

20. Q20.The Conrad Discontinuity separates:

    • A.Crust and Mantle
    • B.Outer and Inner Core
    • C.Upper and Lower Crust✓ Correct Answer
    • D.Upper and Lower Mantle

    Explanation: The Conrad Discontinuity separates the Upper Crust (Sial) from the Lower Crust (Sima).