Chemistry

Chemical Bonding and Molecular Structure

1,277 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 chemistry electrolysis electrolytes and non-electrolytes introduction to electrolysis chemical reactions

Which compounds dissociate to ions, when they dissolved in water?

  1. $BaSO _4; C _2H _4, AgCl$
  2. $KOH; C _6H _6; H _2SO _4$
  3. $Ca _3(PO _4) _2AgI; Cu(NO _3) _2$
  4. $AlCl _3; KOH; O _2$
  5. $KOH; H _2SO _4; KMnO _4$
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Strong electrolytes dissociate completely into ions in water. KOH, H2SO4, and KMnO4 are all strong electrolytes that dissociate fully.

Multiple choice chemistry electrolysis electrolytes and non-electrolytes introduction to electrolysis chemical reactions

Which of the following can be classified as a strong electrolyte?

  1. $\displaystyle { Br } _{ 2 }$
  2. $\displaystyle { C } _{ 6 }{ H } _{ 12 }{ O } _{ 6 }$
  3. $\displaystyle Ca{ Cl } _{ 2 }$
  4. $\displaystyle { H } _{ 2 }O$
  5. $\displaystyle N{ O } _{ 3 }$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Option C is the correct answer.

$CaCl _2$ in aqueous solution dissociates to give one $Ca^{2+}$ and two $Cl^-$ ions.
Any substance which dissociates to form ions can be termed as an electrolyte.
Here Calcium Chloride gives one ion of Calcium and two Chloride ions. That is, from $CaCl _2$ a total of three ions are formed. Hence it can be classified as a strong electrolyte. The strong electrolytes dissociate completely in the solution. Here only $CaCl _2$ is the only compound which completely dissociates.

Multiple choice chemistry electrolysis electrolytes and non-electrolytes introduction to electrolysis chemical reactions

What is an electrolyte?

  1. Electrolytes are substances that dissolve by separating into ions in solution.

  2. Electrolytes are substances that do not conduct electricity but dissolve in water.

  3. Electrolytes are substances that have covalent bonds.

  4. Electrolytes are substances that share electrons.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Electrolyte is an substance that dissolve by separating into ions in solution . They even can conduct electricity. As their ions are free to carry current.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

$\left[ {C{O _2}{{(CO)} _8}} \right]$ displays:

  1. One-Co Co bond, six terminal CO and two bridging CO

  2. One-Co Co bond, four terminal CO and four bridging CO

  3. No-Co Co bond, six terminal CO and two bridging CO

  4. No-Co Co bond, four terminal CO and four bridging CO
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Dicobalt octacarbonyl, Co2(CO)8, in its solid state exists as a bridged structure containing one metal-metal bond (Co-Co), six terminal CO groups, and two bridging CO groups.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Which of the following factors tends to increase the stability of metal ion complexes?

  1. Higher ionic radius of the metal ion

  2. Higher charge/size ratio of the metal ion

  3. Lower ionisation potential of the metal ion

  4. Lower basicity of the ligand
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
For a given ligand, the stability of complexes of metallic ions having the same charge on them decreases with the increase of the size of the central metal ions. Again if the charge of central metal ion is more and the site is small, then the stability of the complex is more. Higher charge/size ratio of metal ion i.e highly charged cation and the smaller cation can form more stable complexes.
Answer will be B.
Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

The V-C distance in ${\text{V}}{\left( {{\text{CO}}} \right) _{\text{6}}}\;{\text{and}}\;\left[ {{\text{V}}{{\left( {{\text{CO}}} \right)} _{\text{6}}}} \right]$ are respectively (in pm) -

  1. 200, 200

  2. 193, 200

  3. 200, 193

  4. 193, 193
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

In V(CO)6 (neutral), the V-C bond is longer due to less back-bonding compared to the [V(CO)6]- anion, where increased back-bonding strengthens the M-C bond and shortens the distance.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Which of the following does not have a metal-carbon bond.

  1. ${C} _{2}{H} _{5}MgBr$
  2. $K[Pt({C} _{2}{H} _{4}){Cl} _{2}]$
  3. $Ni{(CO)} _{4}$
  4. $Al{(O{C} _{2}{H} _{5})} _{3}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Al(OC2H5)3 is an aluminum alkoxide. It contains Al-O bonds, not Al-C bonds. The other options are organometallic compounds containing direct metal-carbon bonds.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Which of the following does not have a metal-carbon bond:

  1. $C _{2}H _{5}MgBr$
  2. $K\left [ Pt \left ( C _{2}H _{4} \right ) Cl _{3}\right ]$
  3. $Ni\left ( CO \right ) _{4}$
  4. $Al\left ( OC _{2}H _{5} \right ) _{3}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal.

$C _2H _5MgBr$ is a $\sigma$-bonded complexes.
$K[Pt(C _2H _4)Cl _3]$ contains a bond between carbon and potassium which is a metal.
$Ni(CO) _4$ also contains metal-carbon bond as it is itself a metal carbonyl.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds
The π acid ligands donate their lone pairs to the metal to form a normal σ bond with the latter in addition to it, the vacant orbitals accept e− from the filled metal orbitals to form a type of π−bond which supplements the σ bond.

Which of the following has lowest C-O bond length ?
  1. $[Ni(CO) _4]$
  2. $[Co(CO) _4]^{-}$
  3. $[Fe(CO) _4]^{2-}$
  4. $[Mn(CO) _6]^+$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This type of bonding where a metal is bonded with the carbon of a carbonyl compound is known as synergic bonding. In a metal carbonyl, the M-C bond has both σ and π character. The ligand donates eΘ pair to the central metal atom, and simultaneously accepts eΘ pair from central metal atom through synergic bonding. Here, all the options are examples of organometallic compounds. Due to synergic bonding, the metal carbon bond strength increases and bond length decreases due to the partial double bond character. Thus, the C-O bond strength decreases and bond length increases and bond order of CO decreases as the number of antibonding electrons increase. Out of the four options, the option D has Mn+, implying that the electron donating nature among the options is minimum. Therefore, tendency of synergic bonding is minimum, and thus M-C bond length is maximum implying that C-O bond strength is maximum and C-O bond length is minimum.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Which of the following is/are example( s) of $\sigma$-bonded organometallic compound ? 

  1. Al$ _2$(CH$ _3$)$ _6$
  2. Pb(CH$ _3$)$ _4$
  3. Zn(C$ _2$H$ _5$)$ _2$

  4. Ferrocene
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Option (A),(B),(C) are correct.Ferrocene is example of organometallic compound but is not $\sigma$-bonded. Its formula is $Fe(C _5H _5) _2$. It is the prototypical metallocene, a type of organometallic chemical compound consisting of two cyclopentadienyl rings bound on opposite sides of a central metal atom. Such organometallic compounds are also known as sandwich compounds. Each cyclopentadienyl (Cp) ring is then allocated a single negative charge, bringing the number of -electrons on each ring to six, and thus making them aromatic. These twelve electrons (six from each ring) are then shared with the metal via covalent bonding. 

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

Which of the following statement(s) is/are incorrect ? 

  1. Metal carbonyls are the examples of only $\sigma$-bonded organometallic complexes.
  2. Metal carbonyls are the examples of only $\pi$-bonded organometallic complexes.
  3. Metal carbonyls are the examples of organometallic complexes which involve both $\sigma$- and $\pi$-bonds between metal and carbon of the carbonyl group.
  4. Metal carbonyls involve both $\sigma$- and $\pi$-bonds between metal and oxygen of the carbonyl group.
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation

Metal carbonyls involve synergistic bonding where the metal donates electrons into the CO pi-antibonding orbital (pi-backbonding) and CO donates electrons into the metal d-orbitals (sigma-bonding). Therefore, they are not examples of only sigma or only pi bonded complexes, making statements A, B, and D incorrect.

Multiple choice chemistry coordination chemistry bonding in metal carbonyls metal carbonyls coordination compounds

If the bond length of the C - O bond in CO is 1.128$\overset{o}{A}$ what is the value of the bond length in [Fe(CO)$ _5$] ?

  1. $1.15$ $\overset{o}{A}$
  2. $1.128$ $\overset{o}{A}$
  3. $1.72$ $\overset{o}{A}$
  4. $1.118$ $\overset{o}{A}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In metal carbonyl complexes like Fe(CO)5, back-bonding from the metal d-orbitals to the pi* antibonding orbitals of CO weakens the C-O bond and increases its bond length compared to free carbon monoxide.