Tag: p-block elements

Questions Related to p-block elements

Which one of the following oxoacids of chlorine is the least oxidising in nature ?

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

  1. $ HClO $

  2. $HClO _2 $

  3. $ HClO _3 $

  4. $HClO _4$

Show answer
Correct Option: D
Explanation:

$HClO _4$ is the strongest oxidizing agent as the oxidation number of chlorine in $HClO _4$ is +7 and it can't afford to lose any more electron.


It can only gain the electrons which result in oxidation of other species.

Hence, the correct option is $D$

Out of the chloric acid ($\displaystyle { HClO } _{ 3 }$) and perchloric acid ($\displaystyle { HClO } _{ 4 }$), $\displaystyle { HClO } _{ 4 }$ is more stable.


State whether the above statement is true or false.

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

  1. True

  2. False

Show answer
Correct Option: A

Which of the following is the correct statement? 

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

  1. $ SO _2 $ is anhydride of sulphuric acid

  2. $ NO _2 $ is anhydride of nitric acid

  3. $ Cl _2O _7 $ is anhydride of perchoric acid

  4. $ P _2O _5 $ is anhydride of orthophosphorus acid

Show answer
Correct Option: C
Explanation:
$Cl _2​O _7​+H _2​O⟶2HClO _4​$

Thus $Cl _2​O _7​$ is an anhydride of perchloric acid.

Option C is correct.

Select the correct statement(s) :

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

  1. The overlap become better when the overlapping orbitals have comparable energy.

  2. The other of increasing tendency of polymerizations $SiO^{4-} _{4}\, >\, PO^{3-} _{4}\, >\, SO^{2-} _{4}\, >\, ClO^{-} _{4}$.

  3. With the increase in positive oxidation state the energy of the 3d-orbitals gradually decreases and it favours the $\pi$-bonding interaction.

  4. The system where the $\pi$ bonding is not effective, the stabilization is attained through the single bonded structure i.e. through the polymerization.

Show answer
Correct Option: A,B,C,D
Explanation:

The overlap become better when the overlapping orbitals have comparable energy. The extent of overlap between orbitals with huge energy difference is insignificant.

The other of increasing tendency of polymerizations $SiO^{4-} _{4}\, >\, PO^{3-} _{4}\, >\, SO^{2-} _{4}\, >\, ClO^{-} _{4}$. This is the same order in which the electronegativity of the central atom increases.

With the increase in positive oxidation state the energy of the 3d-orbitals gradually decreases and it favors the $\pi$-bonding interaction.

The system where the $\pi$ bonding is not effective, the stabilization is attained through the single bonded structure, i.e., through the polymerization. An example is polymer containing $SiO^{4-} _{4}$ tetrahedra.

Which products are expected from the disproportionation of chlorous acid?

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

  1. $HClO _3$ and $Cl _2O$

  2. $HClO _2$ and $ HClO$

  3. $HCl $ and $Cl _2O$

  4. $HClO$ and $HClO _3$

Show answer
Correct Option: D
Explanation:

 Disproportionation reaction of chlorous acid is given as :


$2HClO _2 \rightarrow HClO + HClO _3$

Hence,option D is correct.

The following acids have been arranged in the 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

Show answer
Correct Option: A
Explanation:

Higher the I.E, higher the acidic strength of hypohalus acid (hydroxides)

As we move from top to bottom in halogens the I.E will be decreased,so the acidity will be decreased.
The correct oreder of acidity is I > II > III
Hence option A is correct.

Which of the following has more acidic in nature?

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

  1. HClO

  2. HClO$ _2$

  3. HClO$ _3$

  4. HClO$ _4$

Show answer
Correct Option: D
Explanation:
Acidity of oxyacids of halogen increases with increase in oxidation number of halogen Oxidation number of CI in HCIO is + 1, HCIO$ _2$ is +3, HClO$ _3$ is + 5 and HCIO$ _4$ is + 7.
$\therefore$ HClO$ _4$ is most acidic among given choices.

Assertion: $HClO _4$ is a strong acid than $HClO _3$.
Reason: Oxidation state of Cl in $HClO _4$ is +7 and in $HClO _3$, it is + 5.

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

  1. If both assertion and reason are true and the reason is a correct explanation of the assertion.

  2. If both assertion and reason are true but reason is not a correct explanation of the assertion

  3. If the assertion is true but reason is false

  4. If both the assertion and reason are false

  5. If the assertion is false but the reason is true

Show answer
Correct Option: A
Explanation:

Let us calculate the oxidation state of Cl in $HClO _4$ ;

$+1+ x + $ ($4 \times (-2)$ = 0
So,$ x = -1+8$
         $  = 7$
Hence. the oxidation state of Cl in $HClO _4$ is 7.
Let us calculate the oxidation state of Cl in $HClO _3$ ;
$+1+ x + $ ($3\times (-2)$ $= 0$

So, $x = -1+6$
         $= 5$
Hence. the oxidation state of Cl in $HClO _4$ is 5.

So, we conclude that the oxidation state of Cl is less  in $HClO _3$ than $HClO _4$

Bleaching powder loses its power on keeping for long time because :

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

  1. it changes to calcium hypochlorite.

  2. it changes to calcium chloride and calcium hydroxide.

  3. it absorbs moisture.

  4. it changes to calcium carbonate and chlorine.

Show answer
Correct Option: D
Explanation:

Bleaching powder reacts with carbon dioxide in air to give chlorine and calcium carbonate.

$2Ca(ClO) _2 + 2CO _2 \rightarrow 2CaCO _3 + 2Cl _2 + O _2$

Choose the correct order of acidity order:

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

  1. $\displaystyle { HClO < { HClO } _{ 2 } }$

  2. $\displaystyle { H } _{ 2 }{ SO } _{ 4 } > { H } _{ 2 }{ SO } _{ 3 }$

  3. $\displaystyle { H } _{ 3 }{ PO } _{ 2 } < { H } _{ 3 }{ PO } _{ 3 }$

  4. $\displaystyle { HNO } _{ 3 } > { HNO } _{ 2 }$

  5. $\displaystyle { HF > { HCl } }$

  6. $\displaystyle { H } _{ 3 }{ PO } _{ 3 } > { H } _{ 3 }{ PO } _{ 4 }$

Show answer
Correct Option: A,B,D,F
Explanation:

The acidic character of oxyacids increases with increase in the oxidation state. 


More is the number of $O$ atoms bonded, more electrons will be pulled away from $O-H$ bond, weaker will be the $O-H$ bond and stronger will be the acid. Hence, $\displaystyle
HClO < HClO _2$, $\displaystyle H _2SO _4 > H _2SO _3$ and $\displaystyle HNO _3 > HNO _2$

For options C and F, the correct order is $\displaystyle H _3PO _2 < H _3PO _4 < H _3PO _3$ because  $H _3PO _3$ is polar.

The increase in the acidity is small as the number of unprotonated oxygen, responsible for the enhancement of acidity due to inductive effect remains the same. $HCl$ is more acidic than $HF$ due to strong $H-F$ bond (high bond dissociation enthalpy), high heat of dehydration for $HF$ due to an association in solution due to hydrogen bonding and low electron affinity of fluorine atom.