Tag: oxoacids of halogens

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Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Which has peroxy linkage ?

  1. Perchloric acid

  2. Hypochlorous acid

  3. Para perchloric acid

  4. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Perchloric acid is a mineral acid with the formula HClO₄. Usually found as an aqueous solution, this colorless compound is a stronger acid than sulfuric acid and nitric acid

Hypochlorous acid  $HOCl$ is a weak acid that forms when chlorine dissolves in water, and itself partially dissociates, forming hypochlorite,

| Oxidation state of the halogen inthe acid |                                Oxoacids |  Structure | | --- | --- | --- | | $Cl$ |  $Br$ |  $I$ | |  $+1$ | $HClO$  |  $HBrO$ |  $HlO$ |  $H-O-X$ | |  $+3$ | $HClO _2$ |   |   |  $H-O-x\to O$ | |  $+5$ | $HClO _3$  | $HBrO _3$  | $HlO _3$  |  $H - O - \overset{O}{\overset{\uparrow}{X}} \to O$ | |  $+7$ |  $HClO _4$ |  $HBrO _4$ | $HlO _4$  |  $HO - \underset{O}{\underset{\downarrow}{\overset{O}{\overset{\uparrow}{X}}}} \to O$ |
Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Select correct statements (s):

  1. $ClO _2\ and \ Cl _2O$ are used as bleaching agents for paper pulp and textiles.
  2. $OCl^-$ salts are used as detergents.
  3. $OCl^-$ disproportionates in alkaline medium.
  4. $BrO^- _3$ is oxidised to $Br^-$ in acidic medium.
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

A. The oxides of chlorine such as $ClO _2$  and $Cl _2O$ are used as bleaching agents for paper pulp and textiles. Thus, the option A is correct.

B. $OCl^-$ salts cannot be used as detergents. Thus, the option B is incorrect.

C. In alkaline medium, $OCl^-$ disproportionates. $3ClO^- \xrightarrow {\Delta} 2Cl^-+ClO _3^-$. Thus, the option C is correct.

D. In acidic medium, $BrO _3^-$ is reduced to $Br^-$. $KBrO _3 + 3H _2SO _3 \rightarrow KBr + 3H _2SO _4$ Thus, the option D is incorrect.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Acid strength of oxoacids of halogen is in order :

  1. $ HOF > HOCl > HOBr > HOI $
  2. $ HOI < HOBr < HOCl <HOF $
  3. $ HOI > HOCl > HOBr > HOF $
  4. $ HOCl > HOBr > HOI > HOF $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 The acidic strength of the hypohalous acids increases in the order  : HOI <HOBr <HOCl < HOF.


It is because the electronegativity of halogen decreases down the group.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

In the conversion of $BrO _3 \ ^- $ to $ BrO _4 \ ^- $:

  1. there is no change in oxidation number

  2. reduction takes place in basic solution
  3. reduction also takes place by $XeF _2$
  4. equivalent mass of $ Br{ O }^- _3$ is one-half of ionic mass
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A. During the conversion of $BrO^- _3\ to\ BrO^- _4$, the oxidation number of bromine changes from +5 to +7. Hence, the option A is incorrect.
B. and C.  Since there is an increase in the oxidation number, the net reaction is the oxidation of bromine. Hence, the options B and C are incorrect.
D. The equivalent mass of $BrO^- _3$ is the ratio of the ionic mass to the change in the oxidation number. It is tone half of the ionic mass as the change in the oxidation number is 2. Thus, the option D is correct.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

${ FClO } _{ 3 }$ (perchloryl fluoride) has the highest dielectric constant.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The dielectric constant is the ratio of the permittivity of a substance to the permittivity of free space. It is an expression of the extent to which a material concentrates electric flux, and is the electrical equivalent of relative magnetic permeability.
As the dielectric constant increases, the electric flux density increases, if all other factors remain unchanged. This enables objects of a given size, such as sets of metal plates, to hold their electric charge for long periods of time, and/or to hold large quantities of charge. 
Due to higher electronegativity constituent atoms, $FClO _3$ have very high dieelectric constant.

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Chlorous acid is unstable and decomposes into :

  1. $\displaystyle { HCl,\quad { ClO } _{ 2 } }$
  2. $\displaystyle { HCl,\quad { Cl } _{ 2 } }$
  3. $\displaystyle { HOCl,\quad { ClO } _{ 2 } }$
  4. $\displaystyle { HOCl,\quad { Cl } _{ 2 } }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
It fresh solution is colourless but soon it turns yellow due to formation of $ClO _{2}$

$5HClO _{2}\rightarrow 4ClO _{2}+HCl+2H _{2}O$
Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

The set with correct order of acidity is:

  1. $HClO < HClO _2 < HClO _3 < HClO _4$
  2. $HClO _4 < HClO _3 < HClO _2 < HClO$
  3. $HClO < HClO _4 < HClO _3 < HClO _2$
  4. $HClO _4 < HClO _2 < HClO _3< HClO$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Conjugate base of $HClO, HClO _2, HClO _3, HClO _4$ are  $CLO^-, {ClO _2}^-, {ClO _3}^-, {ClO _4}^-$.


When the atom's size is big, the stability will be more. Hence ${ClO _4}^-$ will be more stable and  ${ClO}^-$ will be the least.

If the conjugate base of an acid is stable, the acid will be stronger (can easily donate protons).

Hence the order will be:

$HClO < HClO _2 < HClO _3 < HClO _4$

Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

The following acids have been arranged in order of decreasing acid strength. Identify the correct order ClOH(I), BrOH(II), IOH(III)

  1. I > II> III

  2. II > I > III

  3. III > II > I

  4. I > III > II
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

As we move down the group basic nature of hydroxides of halogens increases so correct order of decreasing acid strength of hydroxides of halogens is I > II> III
Hence option A is correct.