Question

Molecular Structure and Physical Properties

Consider the following statements and determine which are true and which are false.

true false  NO₃^- has three resonance Lewis structures.
true false  SeF₄ is a polar molecule.
true false  KrF₄ has a see-saw structure.
true false  The formal oxidation state of an atom in a molecule (or molecular ion) can be calculated as:  
(the number of valence electrons on a free atom) minus (half the number of electrons in bonds to that atom) minus (the number of unshared electrons assigned to the atom in the molecule)
true false  Carbon tetrachloride (CCl₄) is a polar molecule.
true false  KrF₄ is a polar molecule.

Answer 1

1. True: NO₃^- has three resonance structures and structures are attached below

2. True: SeF₄ has a see-saw shape and is polar since dipole moments do not cancel out each other

3. False: KrF₄ has square planar structure but not see-saw structure

4. True

5. False; Carbon tetrachloride is a non polar molecule since the dipole moments of bonds cancel out each other.

6.False: KrF₄ has square planar and it is non polar