Tag: p-block elements

Questions Related to p-block elements

The correct order of basic character of oxo anions of chlorine is:

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

  1. $ Cl{O} _{ 4 }^{ - }>Cl{O} _{ 3 }^{ - }>Cl{O} _{ 2 }^{ - }>ClO^{ - }$

  2. $ ClO^- > Cl{O} _2^- > Cl{O} _3^- > Cl{O} _4^- $

  3. $ Cl{O} _3^- > Cl{O} _4^- > Cl{O} _2 > Cl{O}^- $

  4. $ Cl{O}^- > Cl{O} _2^- > Cl{O} _4^- > Cl{O} _3^- $

Show answer
Correct Option: B

The correct statement (s) regarding, $\left( i \right)\,\,HCIO\,\,\,\,\left( {ii} \right)\,\,\,HCI{O _2}\,\,\,\,\left( {iii} \right)\,\,\,HCI{O _3}$ and $\left( {iv} \right)\,\,\,HCI{O _4}$, is 

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

  1. The number of $CI=O$ bond in $(ii)$ and $(iii)$ together is two.

  2. The numbers of lone pairs of electrons on $CI$ in $(ii)$ and $(iii)$ together is three.

  3. The hybridization of $CI$ in $(iv)$ is $s{p^3}$.

  4. Amongst $(i)$ to $(iv)$, the strongest acid is $(i)$.

Show answer
Correct Option: B

Select the incorrect statement(s):

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

  1. ${NF _3}$ has a highest dipole moment among $CO$, ${NH _3}$ and ${NF _3}$

  2. $HF$ has a highest boiling point among ${CH _4}$, ${NH _3}$ and $HF$

  3. ${Cl _2}$ has a lowest boiling point among ${Cl _2}$, ${Br _2}$ and ${I _2}$

  4. ${HClO _3}$ is weakest acid among ${HIO _3}$, ${HBrO _3}$ and ${HClO _3}$

Show answer
Correct Option: A,D
Explanation:

HF has a highest boiling point due to strong H bonding.
$Cl _2$ has a lowest boiling point due to lowest molar mass.
$CO$ has highest dipole moment due to linear structure.

Mixture of $KBr$ and $KBrO _3$ in acidic medium can be used as brominating agent.

The chemical reaction is, $ 5Br^{-} + xBrO^{-} _3 + 6H^{+} \rightarrow 3Br _y + 3H _2O$

Then $ x+y$ is :

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

  1. 6

  2. 3

  3. 5

  4. 11

Show answer
Correct Option: B
Explanation:

Reaction of process:

$ 5Br^{-} + BrO _3^{-} + 6H^{+} \rightarrow 3Br _2 + 3H _2O$
      -1               +5                               0

$x$ = 1 ,$y$ = 2

$x +y$ = 3

Here, bromide ion oxidises and $BrO _3^-$ reduces and bromine forms as a product.

Which one of the following is not a true "per acid" ?

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

  1. $ HClO _4 $

  2. $ H _2SO _5 $

  3. $ H _2S _2O _8 $

  4. $ H _3PO _5$

Show answer
Correct Option: A
Explanation:

A peroxy acid is an acid which contains an acidic -OOH group. $HClO _4$ doesn't contain -OOH group.

Which of the following is the weakest  base as per the Bronsted concept ?

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

  1. $ [ClO _4]^- $

  2. $ [ClO _3]^-$

  3. $ [ClO _2]^-$

  4. $ [ClO]^-$

Show answer
Correct Option: A
Explanation:
The Bronsted-Lowry definition of an acid is a proton donator and a base is a proton acceptor. 

According to Bronsted concept, conjugate base of strongest acid is weakest.

order of acidity $HClO _4 > HClO _3 >HClO _2 > HClO$

so weakest base is $ClO _4^-$.

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 $

Show answer
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

Show answer
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

Show answer
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.

Show answer
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.