Question

The Sial layer is formed of ________ and _________.
A. Silica and Argon
B. Silica and Aluminium
C. Scandium and Argon
D. Sulfur and Argon

Answer 1

Hint: The Sial layer is the upper layer of the Earth’s crust. It is absent in wide oceanic basins because of which it is known as the continental crust. The materials of which this crust is created are less dense than the majority of the earth’s elements, they tend to be concentrated in the uppermost layer of the crust.

Complete answer:
- Option A: Silica and Argon, Argon is a chemical compound and is a gas that is the third most abundant gas in the atmosphere. Hence, this is an incorrect option.
- Option B: Silica and Aluminium are the elements that are found in the Sial layer. The word Sial is made up of Silicate (Si) and Aluminium (Al). The average density of Sial is 2.7 gm/cc and is less than the density of the majority of elements that are found in the earth’s crust because of which Sial is the uppermost layer. Hence, this is the correct option.
- Option C: Scandium and Argon, Scandium is a chemical element and is a rare earth element. Argon is a gas. Hence, this is an incorrect option.
- Option D: Sulfur and Argon, Sulfur is a naturally occurring element and often found in volcanic areas. Argon is a gas. Hence, this is an incorrect option.

So, the correct answer is option B.

Note: The name Sial is the combination of the two elements because of which it is formed. It is found 25km from the surface of the earth. It is thick near the continents and very thin or absent near the ocean floor.