What is the proper nomenclature for CH₂O₂?
The compound you provided can be written more clearly as $\ce{HCOOH}$

IUPAC name : Formic acid

Systematic name :Methanoic Acid

Other names:
Aminic acid, Formylic acid, Hydrogen carboxylic acid, Hydroxymethanone, Hydroxy(oxo)methane, Metacarbonoic acid, Oxocarbinic acid, Oxomethanol