How will you distinguish between the following (give one chemical test):
(a) Chlorobenzene and chlorocyclohexane
(b) Chlorobenzene and benzyl chloride
(c) Ethyl chloride and vinyl chloride
(d) Chlorobenzene and n-hexylchloride
(e) Chloroethane and bromoethane
(f) 3-Bromopropene and 1-bromopropane.

Explanation

(a) Chlorobenzene and chlorocyclohexane. Add a small quantity of aqueous KOH to each compound. Acidify with dil. `HNO_(3)` and add silver nitrate solution.
Chlorocyclohexane when heated with aq. KOH undergoes hydrolysis to give potassium chloride. Potassium chloride reacts with silver nitrate to give white ppt. of AgCl.

Chlorobenzene does not undergo hydrolysis under these conditions to produce phenol and KCl with aq. KOH. Therefore, it does not give white ppt.
(b) Chlorobenzene and benzyl chloride. Same as (a). Benzyl chloride reacts with alcoholic `AgNO_(3)` solution to give white ppt of AgCl while chlorobenzene does not give this test.
`underset("Benzyl chloride")(C_(6)H_(5)CH_(2)Cl)+KOH(aq) overset("Boil")to underset("Benzyl alcohol")(C_(6)H_(5)CH_(2)OH)+KCl`
`KCl + AgNO_(3) to underset("(white ppt)")(AgCl+KNO_(3))`

(c) Ethyl chloride (`C_(2)H_(5)Cl`) and vinyl chloride (`CH_(2)=CHCI`). Ethyl chloride reacts with alcoholic `AgNO_(3)` solution to give white ppt. of AgCl while vinyl chloride does not give this test.
`CH_(3)CH_(2)Cl+KOH(aq) overset("Warm")to underset("Ethanol")(CH_(3)CH_(2)OH)+KCl`
`KCl+AgNO_(3) to underset("(white ppt.)")(AgCl+KNO_(3))`
`CH_(2)=CHCl+KOH(aq) overset("Warm")to "NO reaction"`
This is because alkyl halides (`C_(2)H_(5)CI`) are more reactive than vinyl halides.
(d) Chlorobenzene and n-hexylchloride. Same as (a). n-Hexyl chloride is a haloalkane and gives white ppt, in this test. In contrast, chlorobenzene is aryl halide and does not give white ppt in this test.
`underset("n-Hexyl chloride")(CH_(3)(CH_(2))_(4)CH_(2)Cl)+KOH(aq) overset("Warm")to underset("n-Hexyl alcohol")(CH_(3)(CH_(2))_(4)CH_(2)OH)+KCl`
`KCl + AgNO_(3) to underset("white ppt")(AgCl+KNO_(3))`

(e) Chloroethane and bromoethane. Add a small amount of aqueous KOH to each compound. Acidify with dil, `HNO_(3)` and add a few drops of `AgNO_(3)` solution. A white ppt (AgCl) insoluble in `NH_(4) OH` indicates chloroethane while light yellow ppt. (AgBr) partially soluble in `NH_(4)OH` indicates bromoethane.
`C_(2)H_(5)Cl+KOH(aq) overset("warm")to C_(2)H_(5)OH+KCl`
`KCl+AgNO_(3) to underset("White ppt.")(AgCl+KNO_(3))`
`C_(2)H_(5)Br+KOH(aq) overset("Warm")to C_(2)H_(5)OH+KBr`
`KBr+AgNO_(3) to underset("Pale yellow ppt.")(AgBr)+ KNO_(3)`
(f) 3-Bromopropene (allyl bromide) and 1-bromopropane (alkyl bromide). Add a small amount of dil. alkaline `KMnO_(4)` solution (Baeyer.s reagent) to each compound and shake. 2-Bromopropene (`CH_(2) = CHCH_(2)Br`) decolourises pink colour of `KMnO_(4)` while 1-bromopropane (`CH_(3)CH_(2)CH_(2)Br`) does not.
`underset("3-Bromoprop-1-ene")(CH_(3)=CHCH_(2)Br) overset(Alk. KMnO_(4))to underset("3-Bromopropane-1, 2-diol (Colourless)")(underset(OH)underset(|)CH_(2)underset(OH)underset(|)CHCH_(2)Br)`
`underset("1-Bromopropane")(CH_(3)CH_(2)CH_(2)Br) overset(alc.KOH)to "NO reaction"`.