Which of the following is the correct formula for oxalate?

The formula for oxalate is given as C2O4(2-), which represents its structure accurately. Oxalate is a dianion derived from oxalic acid (H2C2O4), and it consists of two carbon atoms and four oxygen atoms, with an overall charge of -2.

This configuration is significant because it indicates that oxalate can donate two electrons or accept two protons in chemical reactions, playing a vital role in various biochemical processes and reactions. The molecular structure aligns with the characteristic features of oxalic acid, where each carbon atom is bonded to oxygen atoms, forming a structure that includes two carbonyl groups between them.

Considering the other options, the presence of incorrect quantities of carbon and oxygen in those formulas disqualifies them from being the correct representation of the oxalate ion. For example, C2O3(2-) would imply two carbon atoms and three oxygen atoms with a -2 charge, which does not reflect the real structure and charge of oxalate, leading to a misunderstanding of its chemical properties and behaviors.