Which element is the most abundant in Earth's crust by weight?

• A. Iron (Fe)
• B. Silicon (Si)
• C. Aluminum (Al)
• D. Oxygen (O)

Answer: (D)

Verified step by step guidance

1. Understand that the question asks for the most abundant element in Earth's crust by weight, not by number of atoms or volume.
2. Recall that Earth's crust is primarily composed of several elements, with oxygen being a major component due to its presence in many minerals.
3. Recognize that oxygen forms compounds with other elements like silicon and aluminum, which are also abundant but combined with oxygen.
4. Know that oxygen makes up about 46% of the Earth's crust by weight, making it the most abundant element in the crust.
5. Compare the given options (Iron, Silicon, Aluminum) with oxygen and conclude that oxygen surpasses them all in abundance by weight.