Arrange benzene, n-hexane and ethyne in decreasing order of acidic behaviour. Also give reason for this behaviour.

Explanation

The decreasing order of acidic behaviour is ethynegtbenzenegtn-hexane.
the C-H bonds in ehtyne, benzene and hexane is formed by `sp-s,sp^(2)-s` and `sp^(3)-s` overlap respectively. Since sp hydridization carbon which more electronegative than `sp^(2)` hybridization carbon which in trns is more electronegativity than `sp^(3)-` hybridized carbon, therefore the polarity of C-H bond is in the order:
Ethynegtbenzenegthexane
Consequently, the acidity is in the order.
Ethynegtbenzenegthexane