Mesomeric effect is a permanent effect in which $\pi$ electrons are transferred from a

Solution:

The complete displacement of electron pair caused by an atom or a group along a chain by a conjugative mechanism is called the mesmeric effect of that atom or group. It is possible when some multiple bonds are in conjugation (single and double bonds alternatively) or when an atom with at least one lone pair is in conjugation with multiple bond. It is a permanent effect and it operates until conjugation ends. Lone pair and
electrons are involved in it.