2C.17

[Annie Ye]

Select from each of the following pairs of Lewis structures the one that is likely to make the dominant contribution to a resonance hybrid. Explain your selection.

[jeffreygong1I]

For the first pair it is a), as the formal charges of the F and Os are zero(8-(6+4/2)=0, 7-(6+2/2)=0).
For the second pair it is a), as the formal charges of the Os and C are zero(6-(4+4/2)=0, 4-(0+8/2)=0)