A = C6H5CbH2b
C6H5CbH2b + HCl => C6H5CbH2b+1Cl (A')
=> 18 - 12 = 6 CbH2b
=> b+2b = 6 => b =2
=> A = C8H8 = stiren C6H5-CH=CH2
A' = C6H5-CHCl-CH3 = alfa-clorostiren
C6H5-CH=CH2 + HCl => C6H5-CHCl-CH3
B =C6H5CaHb
=> (72+a)/(5+b) = 10,8/1
=> 72+a = 10,8(5+b)
=> 72+a = 54 + 10,8b
=> 10,8b = 18+a
=> b = (18+a)10,8
daca a = 1,=> NU
a = 2=> NU....
daca a = 4 => b = 2
=> C6H5C4H2 sau mai corect HC≡C-C6H4-C≡CH dietinilbenzenul