1.

Which of the follwing represents the decreasing order of K_(a) values ?

Answer»

`(ii)gt(i)gt(iii)gt(IV)`
`(ii)gt(iii)gt(i)gt(iv)`
`(i)gt(ii)gt(iii)gt(iv)`
`(ii)gt(iv)gt(i)gt(iii)`

Solution :In a given structures -
After releasing `H^(+)` from (ii) group , it forms a more STABLE RESONATING structure of carboxylate ion . In case of (i), the anion formed after release of `H^(+)` is more stable due to presence of `e^(-)` withdrawing `NO_(2)` in benzene ring . In(iii), phenoxide ion formed after release of `H^(+)` is more stable in comparison to acetylide ion of group (iv) which is formed after releasing `H^(+)` fromfrom (iv)so ACIDIC ORDER or `K_(a)` is
`(ii)gt(i)gt(iii)gt(iv)`


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