Which of the following elements is a nonmetal that is a homonuclear polyatomic solid?

• A. Carbon
• B. Oxygen
• C. Sulfur
• D. Radon
• E. Cesium

Answer: (C)

Verified step by step guidance

1. First, understand the term 'homonuclear polyatomic solid'. 'Homonuclear' means composed of atoms of the same element, 'polyatomic' means consisting of multiple atoms, and 'solid' refers to the state of matter.
2. Next, identify which of the given elements are nonmetals. Nonmetals are typically found on the right side of the periodic table and include elements like carbon, oxygen, sulfur, and radon.
3. Consider the physical state and molecular structure of each nonmetal element. Carbon can form a homonuclear polyatomic solid in the form of graphite or diamond, but these are not typically referred to as polyatomic solids. Oxygen is a diatomic gas (O₂) at room temperature, not a solid. Radon is a noble gas and does not form polyatomic solids.
4. Sulfur is known to form homonuclear polyatomic solids. It exists naturally as S₈ rings, which are solid at room temperature. This makes sulfur a homonuclear polyatomic solid.
5. Finally, verify that sulfur fits all criteria: it is a nonmetal, forms homonuclear polyatomic structures, and is solid at room temperature. Therefore, sulfur is the correct answer.