There are two lone pairs in the structure of nicotine. in general, localized lone pairs are much more reactive than delocalized lone pairs. with this information in mind, do you expect both lone pairs in nicotine to be reactive?

On the basis of the structure of nicotine, both the lone pair of electrons are localized and do not take part in delocalization. Thus, both the lone pairs are reactive.

A localized lone pair remains near to one atom. A localized bond pair travels amid the two atoms. Resonance hybrids essentially comprise unusual electrons. These electrons step external to the boundaries being set up according to the Lewis theory, and thus are considered as delocalized.