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

Ions form when

  1. protons transfer

  2. electrons transfer

  3. neutrons transfer

  4. energy shells move
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ions are atoms or molecules that have gained or lost electrons, resulting in a net electrical charge. Protons and neutrons remain in the nucleus.

Multiple choice

Which of the following compounds does not undergo Friedel-Crafts reaction?

  1. Chlorobenzene

  2. Toluene

  3. Ethylbenzene

  4. Anisole

  5. Nitrobenzene
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This option is correct because nitrobenzene is formed by the nitration of benzene in the presence of conc. nitric acid and conc. sulphuric acid to form nitrobenzene. It does not react in the presence of anhydrous aluminium chloride. Hence, it does not undergo Friedel-Crafts reaction.

Multiple choice

The ionic radii of N3-, O2-, F-, Na+ follows the order

  1. N3- > O2- > F- > Na+

  2. N3- > Na+ > O2- > F-

  3. Na+ > O2- > N3- > F-

  4. O2- > F- > Na+ > N3-
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Since all the species given in the option are isoelectronic and we know that for isoelectronic species, the ionic radii increases with decrease in nuclear charge and in the given  question the order of decrease of nuclear charge is  N3- > O2- > F- > Na+ which is the same as given in the option .

Multiple choice

Statement 1: O2 molecules are paramagnetic in nature. Statement 2: O2 molecules contain two unpaired electrons in anti-bonding orbitals. Study the above statements carefully and choose the correct option based on these.

  1. Statement 1 is correct. Statement 2 is correct and statement 2 is correct explanation of statement 1.

  2. Statement 1 is correct. Statement 2 is correct and statement 2 is not the correct explanation of statement 1.

  3. Statement 1 is correct. Statement 2 is incorrect.

  4. Statement 1 is incorrect, statement 2 is correct.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

We know that as per the molecular orbital theory,O2 contains two electrons in the anti-bonding orbital if we have a look on the molecular orbital diagram of O2 and hence, it is paramagnetic in nature. Also statement 2 is correct that O2 contains two unpaired electrons in anti bonding orbital, and statement 2 is correct explanation of statement 1 as discussed above. 

Multiple choice

Identify the incorrect statement(s) about peptide linkage.

  1. C-N bond length in peptide link is intermediate in length between typical carbon-nitrogen single bond and carbon-nitrogen double bond.
  2. Peptide bond is planar.
  3. The two alpha carbon atoms attached to C-N are always cis to each other.

  1. Only 1

  2. Only 2

  3. Only 3

  4. Both 1 and 2

  5. Both 2 and 3
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Correct answer. The two alpha carbon atoms attached to C-N are always trans to each other (on the opposite side of the peptide linkage).

Multiple choice

Which of the following sets of molecules are exceptions of octet rule?

  1. SF6, AlCl3, PCl5, CCl4

  2. SF6, PCl3, BCl3, NF3

  3. SF4, NH3, BeCl2, BCl3

  4. SF6, PCl5, BeCl2, BF3

  5. SF4, PCl3, NF3, BF3
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

BeCl2: 4 electron in valence shell of Be ( incomplete octet) BF3: 6 electrons is valence shell of B (incomplete octet) SF6: 12 electrons in valence shell of S (expanded octet). PCl5: 10 electrons in valence shell of P (expanded octet). All of the above are exceptions of octet rule.

Multiple choice

In which of the following ionizing processes, the magnetic moment has changed and the bond order has increased?

  1. H2→ H2+

  2. N2→ N2+

  3. O2→ O2+

  4. F2→ F2-

  5. C2→C2+
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

O2 (16 e-) : ϭ1s2 ϭ*1s2 ϭ2s2 ϭ*2s2 ϭ2pz2 π2px2 π2py2 π*2px1 π*2py1 Bond order = ½ (6 - 2) = 2, diamagnetic O2+ (15 e-) : ϭ1s2 ϭ*1s2 ϭ2s2 ϭ*2s2 ϭ2pz2 π2px2 π2py2 π*2px1 π*2py Bond order = ½ (6 - 1) = 2.5, paramagnetic Magnetic behaviour changes from diamagnetic to paramagnetic Bond order increased.

Multiple choice

Which one of the following statements is/are not false?

  1. The dipole moment of CH3Cl is smaller than that of CH3F.

  2. H2O molecule is linear.

  3. All molecules with polar bonds have dipole moment.

  4. pi-bond is formed by the linear overlapping of p-orbitals.

  5. sp3 hybrid orbitals have equal s and p character.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

F is more electronegative than Cl, so C-F bond is more polar than C-Cl bond. Thus, dipole moment of CH3F is expected to be greater than that of CH3Cl. But the bond length of the C-Cl bond is greater than the C-F bond and hence, the dipole moment of CH3F is smaller.

Multiple choice

Which of the following is/are responsible for Frenkel defect?

  1. The shift of a positive ion from its normal lattice site to an interstitial site

  2. An ion missing from the normal lattice site creating a vacancy

  3. An extra positive ion occupying an interstitial position in the lattice

  4. An extra negative ion occupying an interstitial position in the lattice

  5. Both (3) and (4)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Frenkel defect is caused due to the shift of a positive ion from its normal lattice site to an interstitial site.

Multiple choice

Which of the following sets have only bidentate ligands?

  1. C2O42-, acac, dien, NO2-

  2. EDTA, en, acac, SCN-

  3. en, C2O42-, acac, dmpe

  4. EDTA, dmpe, SCN- , NO2-

  5. dien, acac, dmpe, C2O42-
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

 Ethylenediammine (en): bidentate ligand Oxalate ion (C2O42-): bidentate ligand Acetylacetonate ion (acac): bidentate ligand Dimethylphosphinomethane (dmpe): bidentate ligand Thus, this option is correct.