Which of the following lists contains only metalloids?

• A. Si, As, Sb
• B. Na, Mg, Al
• C. Fe, Cu, Zn
• D. O, S, Se

Answer: (A)

Verified step by step guidance

1. Step 1: Understand what metalloids are. Metalloids are elements that have properties intermediate between metals and nonmetals. They are typically found along the 'stair-step' line on the periodic table between metals and nonmetals.
2. Step 2: Identify the elements in each list and determine their classification as metal, nonmetal, or metalloid. For example, Si (Silicon), As (Arsenic), and Sb (Antimony) are known metalloids.
3. Step 3: Check the first list: Si, As, Sb. All three are metalloids, so this list contains only metalloids.
4. Step 4: Check the other lists: Na, Mg, Al are metals; Fe, Cu, Zn are metals; O, S, Se are nonmetals. None of these lists contain only metalloids.
5. Step 5: Conclude that the list containing only metalloids is Si, As, Sb, based on their position on the periodic table and their characteristic properties.