Chemistry

Chemical Bonding and Molecular Structure

1,420 Questions

This section tests your knowledge of chemical bonding, molecular structure, and hybridization. It covers ionic and covalent bonds, octet rule exceptions, and molecular geometry. These chemistry questions are common in various competitive entrance examinations.

Ionic and covalent bondsHybridisation of elementsOctet rule exceptionsMolecular geometryIntermolecular forces

Chemical Bonding and Molecular Structure Questions

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

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

  1. $ [ClO _4]^- $
  2. $ [ClO _3]^-$
  3. $ [ClO _2]^-$
  4. $ [ClO]^-$
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $ClO _4^-$.
Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

Which one of the following oxyacids of chlorine is the least oxidizing in nature?

  1. $\mathrm{HOCl}$
  2. $\mathrm{H}\mathrm{Cl}\mathrm{O} _{2}$
  3. $\mathrm{H}\mathrm{Cl}\mathrm{O} _{4}$
  4. $\mathrm{H}\mathrm{Cl}\mathrm{O} _{3}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$\overset{+7}{HClO _{4}}$ a is in highest oxidation state so its oxidizing nature is least.

oxidation state $\alpha$ $\frac{1}{oxidising \ nature}$


Option C is correct.

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

Which selection is the correct formula for the chlorate ion?

  1. ${Cl}^{-}$
  2. $Cl{O}^{-}$
  3. $Cl{O} _{2}^{-}$
  4. $Cl{O} _{3}^{-}$
  5. $Cl{O} _{4}^{-}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The correct formula for the chlorate ion is $Cl{O} _{3}^{-}$
The formula $Cl{O}^{-}$ represents hypochlorite ion.
The formula $Cl{O} _{2}^{-}$ represents chlorite ion.
The formula $Cl{O} _{4}^{-}$ represents perchlorate ion.

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

Which of the following does exist?

  1. $HFO _2$
  2. $HClO _2$
  3. $HBrO _2$
  4. $HIO _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$HClO _2$ is a chlorous acid which is oxyacid of halogen.
Remaining oxyacids of halogens do not exist.

Bromous acid $HBrO _2$ and Iodous acid $HIO _2$  and fluorous acid are not likely to exist in nature as they would decompose into oxides and water vapour when trying to isolate them from their respective acid solutions.

Hence, option $B$ is correct.

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

The weakest $Cl-O$ bond is found in :

  1. $ClO _{4}^{-}$
  2. $ClO _{2}^{-}$
  3. $ClO^{-}$
  4. $ClO _{3}^{-}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The anions given are conjugate bases of acids. According to Lowry Bronsted concept, a strong acid has weak conjugate base and a weak acid has a strong conjugate base. These anions are stabilised to greater extent, it has lesser attraction for proton and therefore, will behave as weaker base (lesser tendency for the reaction to go in backward direction). Consequently, the corresponding acid will be strongest because weak conjugate base has strong acid and strong conjgate base has weak acid and vice versa. The charge stabilization increases in the order : $ClO^- < ClO _2^- < ClO _3^- < ClO _4^-$. This means that $ClO^-$ will have minimum stability and therefore, will have maximum attraction for $H^+$. In other words $ClO^-$ will be strongest base and so its conjugate acid HClO will be the weakest acid.

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

Which one is most stable to heat :

  1. $HClO$
  2. $HClO _{2}$
  3. $HClO _{3}$
  4. $HClO _{4}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The thermal stability of the oxyacids of halogens increases with increase in the oxidation state of halogen or with increase in the number of oxygen atoms.
 This is due to involvement of more electrons in the formation of sigma and pi bonds. The multiplicity of the Cl-O bond increases.
Thus the increasing order of the thermal stability is $HClO <HClO _2 <HClO _3<HClO _4$. Thus, $HClO _4$ is most stable to heat.

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

Hypervalent ion is/are :

  1. $SO _3^{2-}$
  2. $PO _4^{3-}$
  3. $SO _4^{2-}$
  4. $ClO _4^{-}$
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Explanation
Hypervalent molecule -
The hypervalent molecule is a molecule that contains one or more main group elements apparently bearing more than eight electrons in their valence shells.

 Explanation -
A. Valence electrons available in $(SO _3)^{2-}$ => 8
B. Valence electrons available in $(PO _4)^{3-}$ => 10
C. Valence electrons available in $(SO _4)^{2-}$ => 12
D. Valence electrons present  in $(ClO _4)^-$ => 14

Hence B, C, D are hypervalent compounds.
Multiple choice oxoacids of halogens p- block elements-ii p-block elements the p-block elements chemistry

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

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

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

Select the correct statement(s) :

  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.
Reveal answer Fill a bubble to check yourself
A,B,C,D Correct answer
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.

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

What are the corresponding anhydrides of the following oxyacids:

$\displaystyle { HClO } _{ 4 }$, $\displaystyle { HClO } _{ 3 }$, $\displaystyle { HClO } _{ 2 }$ and $\displaystyle { HOCl }$.

  1. $\displaystyle { HClO } _{ 4 }:{ Cl } _{ 2 }{ O } _{ 3 }$
  2. $\displaystyle { HClO } _{ 3 }:{ Cl } _{ 2 }{ O } _{ 6 }$
  3. $\displaystyle { HClO } _{ 2 }:{ Cl }O _{ 2 }$
  4. $\displaystyle { HOCl }:{ Cl } _{ 2 }{ O _4 }$
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation
Anhydrides of oxyacids are given as:

$\displaystyle { HClO } _{ 4 }:{ Cl } _{ 2 }{ O } _{ 7 }$

$\displaystyle { HClO } _{ 3 }:{ Cl } _{ 2 }{ O } _{ 6 }$

$\displaystyle { HClO } _{ 2 }:{ Cl }O _{ 2 }$

$\displaystyle { HOCl }:{ Cl } _{ 2 }{ O }$
Multiple choice chemistry further aspects of equilibria dissociation constants ionisation of weak acids and weak bases ionization constants of weak acids and weak bases

Which of the following solutions display common ion effect?

  1. $HCl+NaCl$
  2. ${ H } _{ 2 }S + KH$
  3. $NaHS+HCl$
  4. ${ H } _{ 2 }{ SO } _{ 4 }+{ K } _{ 2 }S$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In common ion effect there should be common ions in the two or more chemicals. Here, $HCl+NaCl$ shows common ion effect. Because $Cl^-$ is common in both.