When gas `A` is passed through dry `KOH` at low temperature, a deep red coloured compound, `B` and a gas care obtained. The gas `A`, on reaction with but-2-ene, followed by treatment with `Zn//H_2 O` yields acetaldehyde. Identify `A, B` and `C`.

Explanation

The reaction of gas `A` with but-2-ene followed by treatment with `Zn//H_2 O` suggests that `A` is `O_3`

Reaction with `KOH`
`2KOH +underset((A)) (5O_(3)) rarr underset(underset(("Deep red coloured"))((B)))(2KO_(3))+underset((C))(5O_(2))+H_(2)O`
Hence A is `O_(3),B` is `KO_(3)` and C is `O_(2)`.