Final answer:
To determine the molecular geometry of polyatomic ions, we can draw their Lewis structures and identify the electron group geometry and molecular geometry.
Step-by-step explanation:
In order to determine the molecular geometry of a polyatomic ion, we need to first draw the Lewis structure. Then, we can identify the electron group geometry and molecular geometry of the ion.
a) CO2-3: The Lewis structure of CO2-3 has a central carbon atom bonded to two oxygen atoms. The electron group geometry is linear and the molecular geometry is also linear.
b) ClO-2: The Lewis structure of ClO-2 has a central chlorine atom bonded to two oxygen atoms. The electron group geometry is bent and the molecular geometry is bent.
c) NO-3: The Lewis structure of NO-3 has a central nitrogen atom bonded to three oxygen atoms. The electron group geometry is trigonal planar and the molecular geometry is trigonal planar.
d) NH+4: The Lewis structure of NH+4 has a central nitrogen atom bonded to four hydrogen atoms. The electron group geometry is tetrahedral and the molecular geometry is also tetrahedral.