Neutral `FeCl_(3)` gives purple colour with `:`

Two isomeric aromatic compounds A and B have the molecular formula C_(7)H_(7)OH . A gives purple colour with FeCl_(3) solution while B does not. What are A and B ?

Two isomeric compounds X and Y have the molecular formula C_(7)H_(7)OH . X gives purple colour with FeCl_(3) while Y does not. What are X and Y ?

The sulphide ion gives purple colour which sodium nitroprusside. The purple colour is due to the formation of: