Question

how can i differ benzene and tolune with a chemical test??

Answer 1

1. Oxidation via KMnO4. Benzene will not show positive results as it does not oxidize while methyl benzene shows positive results and oxidizes to benzolic acid (purple colour solution decolourizes)
An alkylbenzene is simply a benzene ring with an alkyl group attached to it. Methylbenzene is the simplest alkylbenzene.

2. Alkyl groups are usually fairly resistant to oxidation. However, when they are attached to a benzene ring, they are easily oxidised by an alkaline solution of potassium manganate(VII) (potassium permanganate).

Methylbenzene is heated under reflux with a solution of potassium manganate(VII) made alkaline with sodium carbonate. The purple colour of the potassium manganate(VII) is eventually replaced by a dark brown precipitate of manganese(IV) oxide.

The mixture is finally acidified with dilute sulphuric acid.
I hope it helps.