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NEET Chemistry: Kossel Lewis approach Practice Questions

15 free multiple-choice questions on Kossel Lewis approach (Chemical Bonding and Molecular Structure) for NEET Chemistry, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.

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  1. Q1. If the electronegativity difference between two atoms is small, the resulting molecular structure is most likely to exhibit which type of bonding character?

    • ANonpolar covalent
    • BIonic
    • CHighly polarized covalent
    • DDelta bond
    Show answer & explanation

    Correct answer: A — Nonpolar covalent

    Small electronegativity differences imply shared electron density that is nearly equal, resulting in a predominantly nonpolar covalent bond character.

  2. Q2. Consider the O₂ molecule. If the bond order is 2, and we assign the bonding electrons equally, what is the formal charge on each Oxygen atom?

    • A+2
    • B+1
    • C0
    • D-1
    Show answer & explanation

    Correct answer: B — +1

    In O₂, the total valence electrons are 12. Since the bond order is 2, the shared electrons are 2. Each O atom effectively shares 2 electrons, leading to formal charges of +1 and -1.

  3. Q3. The formal charge on an atom in a Lewis structure is calculated using the formula:

    • A(Valence e-) - (Non-bonding e-) - (Shared e-)
    • B(Valence e-) - (Bonding e-)
    • C(Bonding e-) - (Non-bonding e-)
    • D(Valence e-) + (Bonding e-)
    Show answer & explanation

    Correct answer: A — (Valence e-) - (Non-bonding e-) - (Shared e-)

    The formal charge calculation is defined as: (Valence electrons) - (Non-bonding electrons) - (Bonding electrons), which is often simplified as (Valence e-) - (non-bonding e-) - (bonding e-).

  4. Q4. Which scenario indicates that a bond is purely ionic rather than covalent, according to the Kossel-Lewis perspective?

    • AEqual sharing of electrons
    • BLarge electronegativity difference
    • CPartial sharing of electrons
    • DSmall electronegativity difference
    Show answer & explanation

    Correct answer: B — Large electronegativity difference

    A large electronegativity difference implies that electrons are largely transferred rather than shared, characteristic of ionic bonding.

  5. Q5. Which property, according to the Kossel-Lewis approach, is primarily used to predict the nature (ionic or covalent) of a bond?

    • ABond length
    • BBond energy
    • CMolecular geometry
    • DElectronegativity difference
    Show answer & explanation

    Correct answer: D — Electronegativity difference

    The electronegativity difference (ΔEN) between the two bonded atoms is the primary metric used in the Kossel-Lewis approach to classify the type of bond formed (ionic, polar covalent, or nonpolar covalent).

  6. Q6. Which of the following statements correctly describes the relationship between bond polarity and molecular polarity based on Kossel-Lewis concepts?

    • ANonpolar bonds always lead to polar molecules.
    • BBond polarity is independent of molecular polarity.
    • CHighly polar bonds always lead to nonpolar molecules.
    • DPolar bonds can lead to polar or nonpolar molecules depending on geometry.
    Show answer & explanation

    Correct answer: D — Polar bonds can lead to polar or nonpolar molecules depending on geometry.

    While bond polarity is the starting point, the overall molecular polarity (dipole moment) depends crucially on the geometry and the vector sum of individual bond dipoles.

  7. Q7. In the resonance structures of carbonate ion (CO₃²⁻), which structure is the most stable (i.e., has the lowest total formal charge magnitude)?

    • AStructure where C is triple-bonded to one O and single-bonded to two O's.
    • BStructure where C is double-bonded to one O and single-bonded to two O's.
    • CAll structures have identical formal charges, so none is more stable.
    • DStructure where C is single-bonded to two O's and double-bonded to the third O.
    Show answer & explanation

    Correct answer: B — Structure where C is double-bonded to one O and single-bonded to two O's.

    The most stable resonance structure minimizes formal charge magnitude. In the case of CO₃²⁻, structures where the formal charges are ± 1 or ± 2 distributed symmetrically are favored over structures leading to higher localized charges.

  8. Q8. In a molecule where the atoms form highly localized covalent bonds, the tendency to form ionic compounds is primarily governed by the magnitude of the difference in which property?

    • AElectronegativity
    • BBond energy
    • CAtomic radius
    • DMolecular mass
    Show answer & explanation

    Correct answer: A — Electronegativity

    The tendency for electron transfer (ionic bonding) over electron sharing (covalent bonding) is quantified by the difference in electronegativity between the bonding atoms. A larger difference indicates a greater tendency towards ionic character.

  9. Q9. The presence of lone pairs on the central atom in a molecule influences the electron domain geometry, which subsequently affects the molecular geometry. This concept is based on which principle derived from the Kossel-Lewis approach?

    • AValence shell electron pair repulsion
    • BOctet rule
    • CVSEPR theory
    • DBond angle prediction
    Show answer & explanation

    Correct answer: A — Valence shell electron pair repulsion

    The concept that lone pairs occupy space and repel bonding pairs (leading to electron domain geometry) is the foundation of VSEPR theory, which describes molecular shape based on these repulsion effects derived from the distribution of electron pairs.

  10. Q10. Which type of bond is characterized by the complete transfer of electrons, resulting in the formation of ions?

    • AIonic bond
    • BCoordinate bond
    • CMetallic bond
    • DCovalent bond
    Show answer & explanation

    Correct answer: A — Ionic bond

    Ionic bonds form due to the complete transfer of electrons from a metal (low electronegativity) to a non-metal (high electronegativity).

  11. Q11. In a diatomic molecule formed by two atoms with significantly different electronegativities, the bond is predominantly of which character?

    • APurely covalent
    • BNon-polar covalent
    • CIonic
    • DPolar covalent
    Show answer & explanation

    Correct answer: D — Polar covalent

    When there is a large difference in electronegativity between two atoms, the electron density is unequally shared, resulting in a polar covalent bond. If the difference were extremely large, it would be ionic, but for typical diatomic molecules, it falls on the covalent spectrum.

  12. Q12. Which of the following terms is used to denote the charge assigned to an electron in a molecule or ion, based on the Kossel-Lewis approach?

    • AFormal Charge
    • BResonance Charge
    • CBond Charge
    • DValence Charge
    Show answer & explanation

    Correct answer: A — Formal Charge

    Formal charge is the net charge resulting from the distribution of electrons in a molecule or ion, which is central to the Kossel-Lewis approach.

  13. Q13. A bond formed between two atoms with a large electronegativity difference is characterized as:

    • ACovalent
    • BNonpolar
    • CIonic
    • DCoordinate covalent
    Show answer & explanation

    Correct answer: C — Ionic

    A large difference in electronegativity leads to the unequal sharing of electrons, which characterizes an ionic bond.

  14. Q14. If the electronegativity difference (ΔEN) between two atoms is zero, what type of bond is typically formed according to the Kossel-Lewis approach?

    • APolar covalent bond
    • BCovalent bond
    • CMetallic bond
    • DIonic bond
    Show answer & explanation

    Correct answer: B — Covalent bond

    When the electronegativity difference is zero, the shared electron density is equally distributed, resulting in a nonpolar covalent bond.

  15. Q15. In the bond between H and F in the HF molecule, the bond is predominantly polar. What is the approximate bond order for this single bond?

    • A2.0
    • B1.5
    • C0.5
    • D1.0
    Show answer & explanation

    Correct answer: D — 1.0

    A single covalent bond, like H-F, has a bond order of 1.0. Polarity arises from the difference in electronegativity, but the bond order refers to the shared pair of electrons.

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