Fill in the blanks- _____________ is used to separate two immiscible liquids.

Explanation

Chlorine or bromine can be introduced in the benzene ring by treating the diazonium salt solution with corresponding halogen acid in the presence of copper power
`Ar N_2^(+) X^(-) overset(Cu//HCl)(to) ArCl + N_2 + CuX`
`ArN_2^(+) X^(-) overset(Cu//HBr)(to) ArBr + CuX`
This reaction is called Gattermann reaction.