Name one common reagent that can precipitate or react and differentate following pairs:
a. `Ag^(Theta)` and `B^(2+)` b. `Cu^(2+) , Pb^(2+)`
c. `I^(Theta)` and `CI^(Theta)` d. `I^(Theta)` and `Br^(Theta)`
e. `SO_(3)^(2-)` and `SO_(4)^(2-)` i. `Fe^(3+) , Cu^(2+)`
g. `Co^(2+)` and `Cu^(2+)`