hey,

the decreasing order of acidic behaviour of benezene, n-hexane and ethyne is as follows

ethyne>benzene>n-hexane

we determine acidic behaviour depending upon the presence of S-character of C-H bond and due to sphybridization in ethyne , it is 50 percent in bezene it is 33 percent due to sphybridration while in n-hexane it is 25 percent

hope this helps!

Dear,

We know, acidity is directly proportional to S - character , means higher the S - character, higher is the acidity . so, first of all we have to find out hybridisation of all the given compounds and then find then compare the acidity by comparison of S - character . sp³ - hybridized ( 25% , s - character ) < sp² - hybridized ( 33.33%, S - character ) < sp - hybridized ( 50% , S - character ). Hence, it is clear that increasing order of acidity : Ethyne < benzene < n-Hexane

Hope this helps!