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Q: Earth's crust mainly contains-------.
  • A. bauxite
  • B. manganese
  • C. sillica
  • D. iron
Correct Answer: Option C - Like a skin or sheet, the crust is the uppermost layer of earth. The continental crust is 10 to 30 kms thick, and it is mainly composed of Silica and Alumina, (called sial). The oceanic crust is 5 to 10 kms thick, and is mainly composed of Silica and Magnesium (called sima).
C. Like a skin or sheet, the crust is the uppermost layer of earth. The continental crust is 10 to 30 kms thick, and it is mainly composed of Silica and Alumina, (called sial). The oceanic crust is 5 to 10 kms thick, and is mainly composed of Silica and Magnesium (called sima).

Explanations:

Like a skin or sheet, the crust is the uppermost layer of earth. The continental crust is 10 to 30 kms thick, and it is mainly composed of Silica and Alumina, (called sial). The oceanic crust is 5 to 10 kms thick, and is mainly composed of Silica and Magnesium (called sima).