How can we decide the acidity aqnd reactivity of substituted benzene ring ? Some people told me to compare pka values of conjugate bases and some solve problem by electromeric effects at different positions and I am totally confused..please help me out with a SYSTEMATIC method to solve such problem.

'x' gm of a compound A3B2C5 contains 'y' gm of A atoms

 

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how to represent the possible fischer projections for 2-bromohexane