Tag: the p-block elements

Questions Related to the p-block elements

The formula for calcium chlorite is :

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

  1. $ Ca(ClO _4) _2 $

  2. $ Ca(ClO _3) _2 $

  3. $ CaClO _2 $

  4. $ Ca(ClO _2) _2 $

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Correct Option: D
Explanation:

The formula for calcium chlorite is $ Ca(ClO _2) _2 $.Calcium chlorite appears as white granular solid.

Which has peroxy linkage ?

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

  1. Perchloric acid

  2. Hypochlorous acid

  3. Para perchloric acid

  4. None of these

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Correct Option: D
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 | | --- | --- | --- | | $Cl$ |  $Br$ |  $I$ | |  $+1$ | $HClO$  |  $HBrO$ |  $HlO$ |  $H-O-X$ | |  $+3$ | $HClO _2$ |   |   |  $H-O-x\to O$ | |  $+5$ | $HClO _3$  | $HBrO _3$  | $HlO _3$  |  $H - O - \overset{O}{\overset{\uparrow}{X}} \to O$ | |  $+7$ |  $HClO _4$ |  $HBrO _4$ | $HlO _4$  |  $HO - \underset{O}{\underset{\downarrow}{\overset{O}{\overset{\uparrow}{X}}}} \to O$ |

Select the incorrect statement(s).

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

  1. $Cl _2O _6$ is diamagnetic in solid state

  2. $ClO _3$ is paramagnetic

  3. $Cl _2O _6$ is anhydride of $HClO _3$

  4. $ClO _3$ forms dimer due to unpaired electron

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Correct Option: A,C

Select correct statements (s):

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

  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.

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Correct Option: A,C
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.

Acid strength of oxoacids of halogen is in order :

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

  1. $ HOF > HOCl > HOBr > HOI $

  2. $ HOI < HOBr < HOCl <HOF $

  3. $ HOI > HOCl > HOBr > HOF $

  4. $ HOCl > HOBr > HOI > HOF $

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Correct Option: B
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.

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

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

  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

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Correct Option: D
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.

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

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

  1. True

  2. False

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Correct Option: A
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.

Chlorous acid is unstable and decomposes into :

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

  1. $\displaystyle { HCl,\quad { ClO } _{ 2 } }$

  2. $\displaystyle { HCl,\quad { Cl } _{ 2 } }$

  3. $\displaystyle { HOCl,\quad { ClO } _{ 2 } }$

  4. $\displaystyle { HOCl,\quad { Cl } _{ 2 } }$

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Correct Option: A
Explanation:
It fresh solution is colourless but soon it turns yellow due to formation of $ClO _{2}$

$5HClO _{2}\rightarrow 4ClO _{2}+HCl+2H _{2}O$

The set with correct order of acidity is:

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

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

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Correct Option: A
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:

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

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

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

  1. I > II> III

  2. II > I > III

  3. III > II > I

  4. I > III > II

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Correct Option: A
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.