Chemistry Regents Practice Test 2025 – The All-in-One Guide to Exam Success!

A polyatomic ion is specifically defined as an ion that consists of two or more covalently bonded atoms, which together carry a net charge. This characteristic is essential because the atoms within the polyatomic ion are held together by covalent bonds, meaning they share electrons, rather than being a single atom that has lost or gained electrons resulting in a charge, which would be the case in a monatomic ion.

For example, sulfate (SO₄²⁻) and ammonium (NH₄⁺) are common polyatomic ions. Each of these ions is made of multiple atoms bonded together, and they possess an overall charge due to the unequal number of protons and electrons.

The other answer choices do not fit the definition of a polyatomic ion. An ion composed of a single atom with a charge describes a monatomic ion, while an ion that carries a positive charge only refers to cations, which can be either monatomic or polyatomic. The statement that an ion can only exist in a solid state is incorrect, as many ions, including polyatomic ions, can exist in gaseous or aqueous forms under certain conditions. Thus, the defining trait of a polyatomic ion is indeed the presence of multiple covalently bonded