Question: what are the necessary conditions for a system to be aromatic?
Answer: A compound is said to be aromatic if it satisfies the following three conditions: (i) It should have a planar structure. (ii) The π–electrons of the compound are completely delocalized in the ring. (iii) The total number of π–electrons present in the ring should be equal to (4n + 2), where n = 0, 1, 2 … etc.