Question

what is the dominant intermolecular force found between formaldehyde molecules, ch₂o?
red = o, black = c, white = h
dispersion forces
hydrogen bonding
ion - dipole forces
dipole - dipole forces

Explanation:

1. Formaldehyde ($\text{CH}_2\text{O}$) has a trigonal planar geometry with a polar C=O bond, creating a permanent molecular dipole (partial positive on C, partial negative on O).
2. Dispersion forces exist between all molecules but are not dominant here because formaldehyde is polar.
3. Hydrogen bonding requires a molecule to have an H atom bonded to N, O, or F; formaldehyde has H only bonded to C, so hydrogen bonding is not possible.
4. Ion-dipole forces require ions and polar molecules, which are not present between neutral formaldehyde molecules.
5. The dominant intermolecular force between polar neutral molecules is dipole-dipole forces, which arise from attractions between the partial charges of adjacent dipoles.

Answer:

dipole-dipole forces