Correct order of nucleophilicity is

Which of the following correct order of nucleophilicity in gaseous phase

The correct order of nucleophilicity among the following is: (I) CH_(3)-underset(O)underset(||)C-O^(-) (II) CH_(3)O^(-) (III) CN^(-) (iv)

The correct order of nucleophilicity among the following is: (I) CH_(3)-underset(O)underset(||)C-O^(-) (II) CH_(3)O^(-) (III) CN^(-) (iv)

Mark out the incorrect order of nucleophilicity for given nucleophile:

Mark out the incorrect order of nucleophilicity for given nucleophile:

Decreasing order of nucleophilicity is