Which of the following best describes an oxyanion?

• A. A negatively charged polyatomic ion containing oxygen and another element.
• B. A neutral molecule containing oxygen and hydrogen.
• C. A negatively charged ion containing only hydrogen and oxygen.
• D. A positively charged ion composed of only oxygen atoms.

Answer: (A)

Verified step by step guidance

1. Understand the term 'oxyanion': it refers to a type of polyatomic ion that contains oxygen atoms bonded to another element and carries a negative charge.
2. Recall that polyatomic ions are ions composed of more than one atom, and oxyanions specifically include oxygen atoms combined with another element (usually a nonmetal).
3. Recognize that oxyanions are negatively charged because they have gained extra electrons, which is typical for many oxygen-containing ions like sulfate (SO\_4^{2-}) or nitrate (NO\_3^{-}).
4. Differentiate oxyanions from other species: neutral molecules with oxygen and hydrogen (like water, H\_2O) are not ions, ions containing only hydrogen and oxygen (like hydroxide, OH^{-}) are a subset but not all oxyanions, and positively charged ions composed only of oxygen atoms do not exist as common species.
5. Conclude that the best description of an oxyanion is 'a negatively charged polyatomic ion containing oxygen and another element.'