Question

Choose the correct statement(s) regarding the composition of Earth's internal layers:

1. The crust is rich in silica and aluminum (SIAL).

2. The mantle is composed predominantly of nickel and iron.

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

Answer 1

Answer:

A. 1 only

• Correct Answer: Option A) 1 only

• Statement 1: The crust is rich in silica and aluminum (SIAL)- correct

• The Earth's crust, particularly the continental crust, is indeed rich in silica (Si) and aluminum (Al)

• This composition is often referred to as SIAL (Silica-Aluminum)

• The continental crust is composed mainly of granitic rocks which are rich in these elements

• Silica and aluminum are lighter elements that "floated" to the surface during Earth's formation

• Statement 2: The mantle is composed predominantly of nickel and iron - Incorrect

• This statement confuses the mantle with the core

• The mantle is primarily composed of silicate minerals rich in magnesium and iron (often called SIMA - Silica-Magnesium)

• The mantle contains minerals like olivine, pyroxene, and garnet

• It is the core (both outer and inner) that is predominantly composed of nickel and iron (NIFE - Nickel-Iron)

• Earth's Layer Composition Summary:

• Crust: SIAL (Silica-Aluminum) - lightest layer

• Mantle: SIMA (Silica-Magnesium) - intermediate density

• Core: NIFE (Nickel-Iron) - heaviest layer