Question

why there is no mesomeric effect at meta position ?​

Answer 1

Answer:

Mesomeric effect is another term used for Resonance in organic compounds and some inorganic complexes. It is, in effect, the phenomenon of delocalisation of electron clouds. The best example of this effect is Benzene. The pi bond electron clouds of this compound are delocalised over the aromatic ring.

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Answer 2

Because there is no conjugation at meta position see the below anwer you will get it

Hope this helps!!!