 Formaldehyde vibrational data in the NIST Chemistry WebBook

The gas-phase fundamental entries include C=O stretch $1746$, symmetric C–H stretch $2783$, antisymmetric C–H stretch $2843$, and wag $1167\mathrm{c}{\mathrm{m}}^{-1}$, with the $C_{2v}$ labels used in the exam. The listed fundamentals provide an independent assignment check, rather than a solution source.