Question

Each of the compounds shown below has two aromatic rings, labelled as A and B. Identify the number of compounds in which ring B is more active than ring A for electrophilic aromatic substitution reaction ___

Answer 1

If the electron density of ring B is greater than A its means ring B is more reactive than A towards electrophilic substitution reaction.
If electron donating groups are present on B then ring B is more reactive than A and if elctron withdrawing groups are present on ring B, then ring B is less reactive than ring A.