Which two elements are the most abundant in Earth's crust?

• A. Hydrogen and carbon
• B. Oxygen and silicon
• C. Calcium and sodium
• D. Iron and aluminum

Answer: (B)

Verified step by step guidance

1. Understand that the Earth's crust is composed of various elements, but some are much more abundant than others.
2. Recall that oxygen is the most abundant element in the Earth's crust because it forms many compounds, especially oxides and silicates.
3. Recognize that silicon is the second most abundant element, primarily because it forms silicate minerals, which make up a large portion of the crust.
4. Compare the given options and identify that 'Oxygen and silicon' are the two elements that are most abundant in the Earth's crust.
5. Note that other elements like calcium, sodium, iron, aluminum, hydrogen, and carbon are present but in smaller amounts compared to oxygen and silicon.