NCERT MOST IMPORTANT QUESTIONS CLASS – 11 | CHEMISTRY IMPORTANT QUESTIONS PART-1 | CHAPTER -4| CHEMICAL BONDING AND MOLECULAR STRUCTURE | EDUGROWN |

In This Post we are  providing Chapter-4 CHEMICAL BONDING AND MOLECULAR STRUCTURE NCERT MOST IMPORTANT QUESTIONS for Class 11 CHEMISTRY which will be beneficial for students. These solutions are updated according to 2021-22 syllabus. These MCQS  can be really helpful in the preparation of Board exams and will provide you with a brief knowledge of the chapter.

NCERT MOST IMPORTANT QUESTIONS ON CHEMICAL BONDING AND MOLECULAR STRUCTURE

1.Give the main feature of Kossel’s explanation of chemical bonding.

Ans. Kossel in relation to chemical bonding drew attention to the following facts –

(i) In the periodic table, the highly electronegative halogens and the highly electropositive alkali metals are separated by the noble gases.

(ii) In the formation of a negative ion from a halogen atom and a positive ion from an alkali metal, atom is associated with a gain and loss of an electron by the respective atoms.

(iii) The negative and positive ions so formed attain stable noble gas electronic configurations. The noble gases have particularly eight electrons, ns² np⁶.

The –ve and +ve ions are stabilized by electrostatic attraction.

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2.How can you explain the formation of NaCl according to kossel concept?

Ans. The formation of NaCl from sodium and chlorine can be explained as

Na ® Na⁺ + e^–

[Ne] 3s¹ ® [Ne]

Cl + e^– ® Cl^–

[Ne] 3s² 3p⁵ . [Ne] 3s² 3p⁶ or [Ar]

Na⁺ + Cl^– ® Na⁺ Cl^– or NaCl.

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3.Write the significance of octet rule.

Ans. Octet rule signifies –

(i) It is useful for understanding the structures of most of the organic compounds.

It mainly applies to the second period elements of the periodic table.

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4.Write the Lewis structure for CO molecule

Ans. (i) The outer (valence) shell configurations of carbon and oxygen atoms are

Carbon : (6) – 1s² 2s² 2p²

Oxygen : (8) – 1s² 2s² 2p⁴.

The valence electrons (4 + 6 = 10)

But it does not complete octet, thus multiple bond is exhibited.

Thus,

(ii) N (2s² 2p³), O (2s² 2p⁴)

5 + (2 x 6) + 1 = 18 electrons.

Thus,

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5.Give the Lewis dot structure of HNO₃

Ans. HNO₃ ®

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6.What changes are observed in atoms undergoing ionic bonding?

Ans. Due to the electron transfer the following changes occurs –

(i) Both the atoms acquire stable noble gas configuration.

(ii) The atom that loses electrons becomes +vely charged called cation whereas that gains electrons becomes –vely charged called anion.

(iii) Cation and anion are held together by the coulombic forces of attraction to form an ionic bond.

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7.Mention the factors that influence the formation of an Ionic bond.

Ans.Ionic bond formation mainly depends upon three factors –

(i) Low ionization energy – elements with low ionization enthalpy have greater tendency to form an ionic bonds.

(ii) High electron gain enthalpy – high negative value of electron gain enthalpy favours ionic bond.

(iii) Lattice energy – high lattice energy value favours ionic bond formation.

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8.Give reason why H₂⁺ ions are more stable than H₂^– though they have the same bond order.

Ans.In H₂^– ion, one electron is present in anti bonding orbital due to which destabilizing effect is more and thus the stability is less than that of H₂⁺ ion.

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9.How would the bond lengths vary in the following species? C₂, C₂^– C₂^2-.

Ans.The order of bond lengths in C₂ , C₂^– and C₂^2- is C₂ > C₂^– > C₂^2-.

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10.Out of covalent and hydrogen bonds, which is stronger.

Ans. Covalent bond.

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11.Define covalent radius.

Ans. The covalent radius is measured approximately as the radius of an atom’s core which is in contact with the core of an adjacent atom in a bonded situation.

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12.Why NH₃ has high dipole moment than NF₃ though both are pyramidal?

Ans. In case of NH₃ the orbital dipole due to lone pair is in the same direction as the resultant dipole moment of the N-H bonds, whereas in NF₃ the orbital dipole is in the direction opposite to the resultant dipole moment of the three N-F

bonds. The orbital dipole become of lone pair decreases, which results in the low dipole moment.

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13.Draw the resonating structure of NO₃^–

Ans.

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14.On which factor does dipole moment depend in case of polyatomic molecules.

Ans.The dipole moment of the polyatomic molecule depends on individual dipole moments of bonds and also on the spatial arrangement of various bonds in the molecule.

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15.Dipole moment of Be F₂ is zero. Give reason.

Ans. In BeF₂ the dipole moment is zero because the two equal bond dipoles point in opposite directions and cancel the effect of each other.

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