Which of the following elements is classified as a metalloid?

• A. Na (Sodium)
• B. Si (Silicon)
• C. Fe (Iron)
• D. O (Oxygen)

Answer: (B)

Verified step by step guidance

1. Understand the classification of elements: Metals, nonmetals, and metalloids. Metalloids have properties intermediate between metals and nonmetals.
2. Recall that Sodium (Na) is an alkali metal, so it is classified as a metal.
3. Recognize that Iron (Fe) is a transition metal, so it is also classified as a metal.
4. Know that Oxygen (O) is a nonmetal, a typical example of a nonmetallic element.
5. Identify Silicon (Si) as a metalloid because it exhibits properties of both metals and nonmetals, such as semiconducting behavior.