Among these nucleophiles, which of the following orders is correct for their nucleophilicity order in gas phase? - CH , NH , OH ,F (a) - CH >NH >OH >F (b) F OH NH CH (c) - OH >NH >F >CH

Nucleophilicity is the ability of a group to donate electron pairs. Along the same period the nucleophilicity is inversely proportional to the electronegativity of the electron donation atom. Thus, the higher the electronegativity of the atom, the lower is the nucleophilicity. Given anions are: Θ Θ Θ Θ 3 2 C H , N H ,O H,F . The order of the electronegativity of atoms are: F > O > N > C Hence the order of nucleophilicity will be in the reverse order i.e. Θ Θ Θ Θ 3 2 CH > N H > O H> F which is the option (a).