Question

which molecule or ion has a trigonal pyramidal molecular geometry? a) o3 b) krf4 c) nh4+ d) cocl2 e) seo32-

Explanation:

1. For $O_3$, it has a bent molecular geometry due to the presence of a lone - pair on the central oxygen atom and two bonding regions.
2. $KrF_4$ has a square - planar molecular geometry as the central Kr atom has 6 electron - pairs (4 bonding pairs and 2 lone - pairs) following VSEPR theory.
3. $NH_4^+$ has a tetrahedral molecular geometry as the central N atom has 4 bonding pairs and no lone - pairs.
4. $COCl_2$ has a trigonal planar molecular geometry with the central C atom having 3 bonding regions and no lone - pairs.
5. $SeO_3^{2 - }$ has a trigonal pyramidal molecular geometry. The central Se atom has 4 electron - pairs (3 bonding pairs and 1 lone - pair). According to VSEPR theory, when a central atom has 3 bonding regions and 1 lone - pair, the molecular geometry is trigonal pyramidal.

Answer:

e) $SeO_3^{2 - }$