Question

Choose the correct statement(s) regarding the lithosphere and asthenosphere:

1. The lithosphere includes both the crust and the entire mantle.

2. The asthenosphere plays a role in plate tectonic movement.

• A. 1 only
• B. 2 only
• C. Both 1 and 2
• D. Neither 1 nor 2

Answer 1

Answer:

B. 2 only

• Correct Answer: Option B) 2 only

• Statement 1: The lithosphere includes both the crust and the entire mantle.This statement is incorrect. The lithosphere consists of the crust and only the uppermost portion of the mantle (specifically the upper rigid part). It does not include the entire mantle. The lithosphere is the rigid outer shell of the Earth, typically extending to a depth of about 100 kilometers.

• Statement 2: The asthenosphere plays a role in plate tectonic movement.This statement is correct. The asthenosphere is a semi-molten, plastic layer in the upper mantle that lies beneath the lithosphere. Its semi-fluid nature allows the rigid lithospheric plates to move over it, making plate tectonic movement possible. The convection currents in the asthenosphere drive the movement of tectonic plates.

• Key Points to Remember:

• Lithosphere: Rigid outer layer consisting of crust + upper mantle (not entire mantle)

• Asthenosphere: Semi-molten layer beneath lithosphere that enables plate movement

• The boundary between lithosphere and asthenosphere is defined by temperature and mechanical properties, not chemical composition

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