Pblock Elementsii Result Question 11
11. Among the following oxoacids, the correct decreasing order of acidic strength is
(2014 Main)
(a) $\mathrm{HOCl} > \mathrm{HClO} _2 > \mathrm{HClO} _3 > \mathrm{HClO} _4$
(b) $\mathrm{HClO} _4 > \mathrm{HOCl} > \mathrm{HClO} _2 > \mathrm{HClO} _3$
(c) $\mathrm{HClO} _4 > \mathrm{HClO} _3 > \mathrm{HClO} _2 > \mathrm{HOCl}$
(d) $\mathrm{HClO} _2 > \mathrm{HClO} _4 > \mathrm{HClO} _3 > \mathrm{HOCl}$
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Answer:
Correct Answer: 11. ( c )
Solution:
Decreasing order of strength of oxoacids
$\mathrm{HClO} _4 > \mathrm{HClO} _3 > \mathrm{HClO} _2 > \mathrm{HOCl}$
Reason Consider the structures of conjugate bases of each oxyacids of chlorine.
Negative charge is more delocalised on $ ClO _4 ^ - $ due to resonance, hence, $ClO _4 ^ - $ is more stable (and less basic)..
Hence, we can say as the number of oxygen atom(s) around Cl -atom increases as oxidation number of Cl -atom increases and thus, the ability of loose the $\mathrm{H}^{+}$increases.
BETA
