Which of the following arrangements gives the correct order of increasing basic character of the conjugate bases of the oxoacids of chlorine?

Options

A. `CIO_(4)^(-) lt CIO_(3)^(-) lt CIO_(2)^(-) lt CIO^(-)`
B. `CIO^(-) lt CIO_(2)^(-) lt CIO_(3)^(-) lt CIO_(4)^(-)`
C. `CIO_(4)^(-) lt CIO_(3)^(-) lt CIO^(-) lt CIO^(2)`
D. `CIO_(3)^(-) lt CIO_(4)^(-) lt CIO_(2)^(-) lt CIO^(-)`

Answer

1

Explanation

Oxacids are ternary acids containing oxygen. For all the common inorganic acids the ionisable `H` atoms are covalently bonded to oxygen atoms.In a series of oxacids of one element there is a correlation between acid strength and the number of oxygen atoms.Electronegativity arguments can be used to provide an explanation
Oxyacids are like the hydroacids acids in that their acid strength depends on the weakness of the covalent bond between the ionisable `H` atoms and its neighbour For the oxyacids the greater the number of highly electronegative oxygen atoms the more the electrons density is pulled away from the `H` atoms and the weaker the hydrogen -oxygen bond.

As a result an acid with numerous oxygen atoms is more easily ionized and hence stronger.
In other words the strength of oxoacids of `Cl` increases appreciably with increase in the oxidation state of the `Cl`. Thus hypochlorous acis is very weak `(pk_(a)= 7.5)` chlorous acid weak `(pk_(a)=2.0)`, chloric acid strong `(pk_(a)=-1.2),` and perchloric acid very strong `(pk_(a)=-10)`. Consequently the conjugate base of `HClO` will be the strongest while the conjugate base of `HClO_(4)` will be the weakest.
The strength of oxoacids with the same oxidation state of the halgons decrease in the sequences,
`H-O-F gt H-O-Cl gt H-O-Br gt H-O-I`
due to the decrease to electronegativity of halgons.