Question -
Answer -
Electrophiles areelectron-deficient species and can receive an electron pair. On the other hand,nucleophiles are electron-rich species and can donate their electrons.
Here, HO– actsas a nucleophile as it is an electron-rich species, i.e., it is anucleus-seeking species.
Here, –CNacts as a nucleophile as it is an electron-rich species, i.e., it is anucleus-seeking species.
Here, 
acts as an electrophileas it is an electron-deficient species.