Question

which of the following is both an anion and a compound?
hco₃⁻
nacl
k⁺
cl⁻
na⁺

Explanation:

An anion is a negatively - charged ion. A compound is a substance made up of two or more different elements. $HCO_3^-$ is a polyatomic anion (bicarbonate ion) composed of hydrogen (H), carbon (C), and oxygen (O), so it is both an anion and a compound. $NaCl$ is a compound but not an anion. $K^+$ and $Na^+$ are cations (positively - charged ions). $Cl^-$ is an anion but a single - element ion, not a compound in the sense of being made of multiple different elements combined in a molecule.

Answer:

$HCO_3^-$