In which of the following homolytic bond fission takes place?

chlorination of CH4 is free radical reaction and the mechanism is free radical reaction mechanism→ Addition of HBr to double bond is electrophilic addition reaction [Heterolytic cleavage take place]→ Alkaline hydrolysis of ethyl chloride is nucleophilic substitution reaction [Hetrolytic cleavage takes place].→ Nitration of benzene is electrophilic substitution reaction [heterolytic cleavege takes place]