Compound (A) of molecular formula `C_(7)H_(8)` when treated with air in presence of `V_(2)O_(5)` at 773 K gives a compound (B) of molecular formula `C_(7)H_(6)O`, which has the smell of bitter almonds. Alkaline `KMnO_(4)` oxidises compound (B) to ( C) of molecular formula `C_(7)H_(6)O_(2)`. Compound (B) on treatment with `N_(2)H_(4)` and KOH gives back compound (A). Identify (A), (B) & ( C) and explain the reactions.

Explanation

(i) Compound A is Toluene `(C_(6)H_(5)CH_(3))`.
(ii) When toluene is treated with air in the presence of `V_(2)O_(5)` at 773K. It gives compound B benzaldehyde `(C_(6)H_(5)CHO)`.
`underset((A))(C_(6)H_(5)CH_(3))underset("air"//V_(2)O_(5)773K)overset((O))tounderset((B))(C_(6)H_(5)CHO)+H_(2)O`
(iii) Alkaline `KMnO_(4)` oxidises Benzaldehyde (B) to Benzoic acid (C).
`underset((B))(C_(6)H_(5)CHO)overset((O))tounderset((C))(C_(6)H_(5)COOH)`
(iv) Benzaldehyde (B) on treatment with `N_(2)H_(4)` and KOH gives compound A toluene.
`underset((B))(C_(6)H_(5)CHO)underset(N_(2)H_(4)//KOH)tounderset((A))(C_(6)H_(5)CH_(3))`