The bonds are arranged trigonally around the selenium atoms, but the structure is polymeric.
CO32- is trigonal planar, bond angles are 1200
Carbonate ion is in a trigonal planar shape (hint: sp2 hybridization)
Formaldehyde has a nonpolar trigonal planar molecule.
Bromine gas is linear because there is only two atoms involved in the molecule.
Not linear.
Sulfur tetraoxide is a trigonal planar. There is the sulfur in the middle and three oxygen that surrounds it with all of them a double bond linking them to the sulfur.
Trigonal Planar
nh3
Selenium dioxide has a bent molecule.
nh3
Trigonal planar
Trigonal Pyramidal. It is not trigonal planar because there is one lone pair around the central atom, just like the shape of ammonia.