Answer:

Introduction:
In chemistry, electrophiles are the species that are attracted towards the electron-rich centers and nucleophiles are the species that are attracted towards the electron-deficient centers. The behavior of a compound as an electrophile or nucleophile depends on the presence of electron-rich or electron-deficient centers in the compound.

Explanation:
Out of the given compounds, only the cyanide ion (CN-) behaves as an electrophile as well as a nucleophile. This is because of the presence of an electronegative carbon atom and a lone pair of electrons on the nitrogen atom in the cyanide ion.

Electrophilic Behavior:
The carbon atom in the cyanide ion is electrophilic due to the partial positive charge developed on it by the withdrawal of electrons towards the highly electronegative nitrogen atom. This makes the carbon atom susceptible to attack by nucleophiles.

Nucleophilic Behavior:
The nitrogen atom in the cyanide ion is nucleophilic due to the presence of a lone pair of electrons. This lone pair of electrons can be donated to an electron-deficient center, making the cyanide ion a nucleophile.

Other Compounds:
Acetone, nitrite ion, and sulfite ion do not have electron-rich or electron-deficient centers that can make them behave as both electrophiles and nucleophiles.

Conclusion:
In summary, the cyanide ion is the only compound among the given options that behaves as both an electrophile and a nucleophile due to the presence of an electronegative carbon atom and a lone pair of electrons on the nitrogen atom.

Answer is acetone
because in a typical aldo condensation reaction.The acetone acts as both nucleophile and electrophile.
cyanide ion is nucleophile
nitrite is electrophile
sulphite ion is nucleophile