Which category does the ion PO4^{3-} belong to?

• A. Ammonium ion
• B. Hydride ion
• C. Halide ion
• D. Oxoanion

Answer: (D)

Verified step by step guidance

1. Identify the ion given: PO4^{3-}, which is the phosphate ion.
2. Recall the definitions of the categories: Ammonium ion is NH4^{+}, Hydride ion is H^{-}, Halide ions are the halogen ions like Cl^{-}, Br^{-}, I^{-}.
3. Recognize that PO4^{3-} contains oxygen atoms bonded to phosphorus, making it an ion with oxygen atoms attached to a central atom.
4. Understand that ions consisting of oxygen atoms bonded to another element with a negative charge are called oxoanions.
5. Conclude that PO4^{3-} fits the definition of an oxoanion, as it is a polyatomic ion with oxygen atoms bonded to phosphorus carrying a negative charge.