Why phosgene has a smaller dipole moment than formaldehyde?

Phosgene has a smaller dipole moment than formaldehyde because its dipole moments cancel each other out due to the symmetry of the molecule. In phosgene, the dipole moments of the C=O bonds are in opposite directions, resulting in a net dipole moment close to zero. In contrast, formaldehyde has a larger dipole moment because the oxygen atom exerts a greater pull on the electrons in the C=O bond, creating a larger net dipole moment.