MDCAT/ECAT/FSC Chapter-wise High-Yield Chemistry MCQs Quiz on Chemical Bonding Set II

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MDCAT/ECAT/FSC Chapter-wise High-Yield Chemistry MCQs Quiz on Chemical Bonding Set II

Interactive MCQ Quiz
🔥🌟 Grand Chemistry Interactive MCQs Quiz Test on Chemical Bonding for Class FSC/MDCAT/ECAT Set II 🧪💡 | Learn & Practice!
1. How many valence electrons are transferred from the nitrogen atom to potassium in the formation of the compound potassium nitride?

✅ Correct Answer: (a)

Explanation:

Nitrogen has 5 valence electrons and needs 3 to complete its octet → N³⁻.

Potassium is monovalent (K⁺). Formula is K₃N to balance charges.

Thus, 3 electrons are transferred to nitrogen from three potassium atoms.

2. What is the total number of electrons in the correct Lewis dot formula of the sulfite ion (SO₃²⁻)?

✅ Correct Answer: (d)

Explanation:

S has 6 valence e⁻ + 3×O (18) + 2 extra = 26 total.

3. The valence shell of element ‘A’ contains 3 electrons while the valence shell of element ‘B’ contains 6 electrons. If ‘A’ combines with ‘B’, the probable formula of the compound formed will be

✅ Correct Answer: (c)

Explanation:

Element A has 3 valence electrons is trivalent with EC ns² np¹ → forms A³⁺.

Element B has 6 valence electrons is bivalent with EC ns² np⁴ → forms B²⁻.

To balance charges (+6 and −6), 2 A³⁺ combine with 3 B²⁻ → A₂B₃.

4. Which compound has the greatest total number of lone pairs of electrons in the valence shell of all of its atoms?

✅ Correct Answer: (b)

Explanation:

CO₂ has two oxygen atoms, each with 2 lone pairs → total 4 lone pairs, which is greater than CH₃Cl (3 lone pairs), N₂H₄ (2 lone pairs), and NH₄CN (1 lone pair).

5. 1 coulomb is equal to:

✅ Correct Answer: (b)

Explanation:

1 coulomb =2.99 × 10⁹ e.s.u

6. 1 debye (1D) is equal to:

✅ Correct Answer: (d)

Explanation:

All three given values are equivalent representations of 1 Debye. 1 Debye = 3.33564×10⁻³⁰C·m = 10⁻¹⁸esu·cm = 10⁻¹⁰esu·m.

7. The maximum number of electron with clock-wise spin that can be accommodated in “N” shell is

✅ Correct Answer: (d)

Explanation:

The maximum number of electrons in ‘N’ shell is 32 (2n2). Since electrons are always in pair in orbitals with opposite spins. Hence half electron have clock-wise spin and other half have anti-clock wise spin i.e. 16 electrons out of 32 have clock-wise spins and other 16 have anti-clock-wise spins.

8. Amongst HX, the maximum dipole moment is of

✅ Correct Answer: (a)

Explanation:

Dipole moment is directly proportional to the polarity of molecule, which in turn is proportional to the ∆EN. The HF has most polar covalent bond due to greatest ∆EN (1.9).

9. The most paramagnetic element is

✅ Correct Answer: (a)

Explanation:

When placed in a magnetic field, paramagnetic materials tend to become weakly magnetized in the direction of the magnetizing field. Most atoms or ions with incompletely filled atomic orbitals are paramagnetic due to the presence of unpaired electrons in the substance. Unpaired electrons have a magnetic dipole moment and act like small magnets because of their spin. The atom with greater number of unpaired electron will be most paramagnetic.

Electronic Configuration of Manganese …….[Ar] 3d⁵ 4s² (5 unpaired electrons)

Electronic Configuration of Cobalt …………… [Ar] 3d⁷ 4s² (3 unpaired electrons)

Electronic Configuration of Iron ………………. [Ar] 3d⁶ 4s² (4 unpaired electrons)

Electronic Configuration of Chromium …….[Ar] 3d⁵ 4s¹ (6 unpaired electrons)

Chromium has 6 unpaired electrons in its d- and s-orbitals. So, it will show maximum Paramagnetism.

10. Which among the following have triple bonds? (I) NO₃⁻ (II) HCN (III) CO (IV) CH₃CN

✅ Correct Answer: (d)

Explanation:

(II) HCN……H–C≡N (III) CO …… C≡O (IV) CH₃CN…….. CH₃–C≡N

11. Among the following the lowest degree of Paramagnetism per mole of the compound at 298 K will be shown by

✅ Correct Answer: (b)

Explanation:

Valence Shell EC of Mn²⁺ of ion = 3d⁵ (5 unpaired electron)

Valence Shell EC of Cu²⁺ of ion = 3d⁸ (1 unpaired electron)→ lowest degree of Paramagnetism

Valence Shell EC of Fe²⁺ of ion = 3d⁶ (4 unpaired electron)

Valence Shell EC of Ni²⁺ of ion = 3d⁸ (2 unpaired electron)

Least Paramagnetism is shown by that specie which contains least number of unpaired electrons. Hence CuSO₄.5H₂O with least number of unpaired electron exhibit lowest degree of Paramagnetism.

12. Which one of the following elements has valence electrons in the n = 3 shell?

✅ Correct Answer: (b)

Explanation:

EC of ₁₄Si is [Ne], 3s² 3p² shows that its valence electrons lies in 3rd orbit (n=3).

13. Which one of the following species contains an unpaired electron?

✅ Correct Answer: (d)

Explanation:

NO₂ is an odd electron molecules has only 7 valence electrons around it.

14. Which of the following pairs do not form a coordinate covalent bond with each other?

✅ Correct Answer: (d)

Explanation:

Carbon cannot form coordinate covalent bond due to lack of lone pair and empty orbital.

15. Number of shared electron pairs in ethane are

✅ Correct Answer: (c)

Explanation:

✨There are 7 sigma bonds in ethane (C₂H₆) 6 C–H bonds and 1 C–C bond. 👉→ 7 shared electron pairs in total.

16. Which of the following species contains delocalized π electrons?

✅ Correct Answer: (d)

Explanation:

✨ Ozone, benzene, and carboxylate ion all have resonance structures where Ï€ electrons are spread over multiple atoms. Hence, all of them contain delocalized Ï€ electrons. → 👉 The correct answer is d.

17. In metal-ligand complexes like [Cu(NH₃)₄]²⁺, the Cu–N bonds are:

✅ Correct Answer: (b)

Explanation:

✨In the complex [Cu(NH₃)₄]²⁺, copper (Cu²⁺) acts as a central metal ion, and each ammonia (NH₃) molecule acts as a ligand. Ammonia has a lone pair on nitrogen, which it donates to the empty orbitals of Cu²⁺. This donation forms a coordinate covalent bond (also called a dative bond), where both electrons in the bond come from the ligand. This is a classic Lewis acid–base interaction, where:

Cu²⁺ (metal ion) → Lewis acid (electron pair acceptor)

NH₃ (ligand) → Lewis base (electron pair donor)

Thus, the Cu–N bonds are coordinate covalent bonds (also called dative bonds).

18. Which of the following contains a coordinate covalent bond?

✅ Correct Answer: (a)

Explanation:

✨ In CO, the C→O bond involves a lone pair from oxygen donated to carbon (besides normal covalent bonding).

19. In the ammonium ion (NH₄⁺), the fourth N–H bond is formed by:

✅ Correct Answer: (b)

Explanation:

✨ In NH₄⁺ (ammonium ion), three N–H bonds are normal covalent bonds formed by mutual sharing electrons. The fourth N–H bond is a coordinate covalent (dative) bond, formed when nitrogen donates its lone pair to the proton (H⁺), which has no electrons to share.

20. In a Lewis acid-base reaction, the coordinate bond is formed when:

✅ Correct Answer: (b)

Explanation:

✨ In a Lewis acid-base reaction, a Lewis base (e.g., NH₃, H₂O, OH⁻) is an electron pair donor, and a Lewis acid (e.g., H⁺, BF₃, AlCl₃, metal ions) is an electron pair acceptor. The coordinate covalent bond forms when the base donates a lone pair to the acid, which has an empty orbital ready to accept it.

21. Once formed, a coordinate covalent bond behaves as:

✅ Correct Answer: (d)

Explanation:

✨A coordinate covalent bond is different only in the way it is formed (one atom donates both electrons).

Once formed, it’s indistinguishable from a regular covalent bond in terms of:

Same bond strength

Same bond length

Same Chemical behavior

Example: In NH₄⁺, the fourth N–H bond is coordinate in origin, but all four N–H bonds are identical.

22. Which of the following has the shortest C−C bond length?

✅ Correct Answer: (a)

Explanation:

✨ Bond length varies inversely with bond order. Since bond order of C₂H₂ is 3 (showing C≡C), the C–C bond length is shortest in C₂H₂.

23. Which of the following has the highest bond energy?

✅ Correct Answer: (c)

Explanation:

✨ Bond energy varies directly with bond order. Since bond order of C₂H₂ is highest i.e. 3 (showing C≡C), the C–C bond energy is highest in C₂H₂.

24. Oxygen-oxygen bond length in ozone is same because of

✅ Correct Answer: (c)

Explanation:

✨ The presence of same bond lengths between two different bonds of two atoms indicates resonance.

25. The bond angle in the ammonium ion is equal to

✅ Correct Answer: (c)

Explanation:

✨ Ammonium ion (NH₄⁺) is AB₄ type specie whose shape must be tetrahedral with bond angel of 109°.28.

26. Among halogen molecules, which has the lowest bond dissociation energy?

✅ Correct Answer: (c)

Explanation:

✨F₂ has the lowest bond dissociation energy (violating the group trend of bond energy) among halogen molecules due to weakest bond due to lone pair repulsion.

Bond dissociation energy (BDE) generally decreases down the group in halogens (Cl₂ > Br₂ > I₂ > F₂), because bond length increases and bonds get weaker. But F₂ is an exception:

F atoms are very small → strong lone pair–lone pair repulsions in the F–F bond.This makes the F–F bond unusually weak, despite being very short.

Approximate bond energies (kJ/mol):

F₂ → 158 (weakest)

Cl₂ → 243 (strongest)

Br₂ → 193

I₂ → 151

27. The bond angle in H₂O and CO₂ are respectively:

✅ Correct Answer: (c)

Explanation:

Ammonium ion (NH₄⁺) is AB₄ type specie whose shape must be tetrahedral with bond angel of 109°.28.

✨H₂O (water): Central atom O has 2 bond pairs (O–H) + 2 lone pairs. According to VSEPR theory, lone pairs repel more strongly than bond pairs. This compresses the bond angle from the ideal tetrahedral 109.5° to ~104.5°.

✨CO₂ (carbon dioxide): Central atom C has 2 double bonds and no lone pairs. Electron pairs arrange linearly to minimize repulsion. Bond angle = 180°.

28. Which has the largest bond angle?

✅ Correct Answer: (d)

Explanation:

✨All (CO₂, CS₂, BeCl₂) are linear with equal largest bond angle of 180°.

CO₂: O=C=O (sp hybridization, double bonds, linear, 180°)

CS₂: S=C=S (sp hybridization, double bonds, linear, 180°)

BeCl₂: Cl–Be–Cl (sp hybridization, linear, 180°)

29. The bond energy of hydrogen bond ranges

✅ Correct Answer: (c)

Explanation:

✨ Hydrogen bond is a secondary bond. Its bond energy ranges 3-10 kcal. The bond energy of hydrogen bonds is only 20-40 or 4-50 kJ/mol as compared to bond energy of 150–500 kJ/mol for normal covalent bond.

30. The nature of inter-particle forces in benzene is

✅ Correct Answer: (d)

Explanation:

✨ Non-polar molecules like Benzene has only dispersion forces among its molecule.

31. Maximum hydrogen bonds in water are

✅ Correct Answer: (d)

Explanation:

✨The maximum number of molecules that one water molecule can hold through hydrogen bonding is 4 because the two hydrogen atoms of water can form two hydrogen bonds and the two lone pairs on oxygen can also form two hydrogen bonds. Thus, each water molecule participates in a tetrahedral hydrogen-bonding network

A single H₂O molecule can form four hydrogen bonds in total:

2 bonds donated → 2 donor sites from its two hydrogen atoms.

2 bonds accepted → 2 acceptor sites from its two lone pairs on oxygen.

32. In benzene, the C–C bond length is:

✅ Correct Answer: (c)

Explanation:

✨In benzene (C₆H₆), the carbon-carbon bonds are resonance hybrids of single and double bonds (i.e. benzene’s bonds are neither single nor double) with intermediate equal length. Due to delocalization of Ï€ electrons across the entire ring, all six C–C bonds are identical in length and strength. As a result, all C–C bonds are equivalent, with bond order = 1.5.

Bond length values:

C–C single bond ≈ 1.54 Ã…

C=C double bond ≈ 1.34 Ã…

C–C in benzene ≈ 1.39 Ã… (intermediate).

33. The bond angle in NH₃ is smaller than in CH₄ because:

✅ Correct Answer: (a)

Explanation:

✨ Lone pair–bond pair repulsion in NH₃ reduces angle (107° vs 109.5°)

34. In which one of the following does ionic bonding occur between named atoms?

✅ Correct Answer: (d)

Explanation:

✨ Generally, an ionic bond is formed b/w atoms of electropositive elements of low IP and atoms of electronegative element of high EA. The difference in electronegativity more than 1.7 is the deciding factor for ionic bond formation. Sodium and hydrogen with of 1.7 will form ionic bond in sodium hydride.

35. How many bonding and non-bonding electron pairs are found in the BF₃ molecule?

✅ Correct Answer: (c)

Explanation:

✨ Boron has 3 valence electrons. So it can form 3 covalent bonds with 3 fluorine atoms to form BF₃ molecule. Thus in BF₃ there are 3 bonding electron pairs with no non-bonding electron pair.

36. Only London dispersion forces are present among the

✅ Correct Answer: (c)

Explanation:

✨ Iodine being molecular solid can only have London dispersion forces as the only intermolecular force.

37. The carbon atoms in calcium carbide (dicarbide) are held by

✅ Correct Answer: (d)

Explanation:

✨ Carbide ion also called acetylide ion (C₂²⁻) is derived from acetylene containing C≡C bond by removing its two H atoms. In Calcium carbide (CaC₂), the C₂²⁻ ion has a triple bond between the two carbon atoms, consisting of one sigma and two pi bonds. Therefore, the carbon atoms in calcium carbide are held together by two Ï€ bonds and one σ bond.

38. Which carbon is more electronegative?

✅ Correct Answer: (c)

Explanation:

✨ sp-hybridized carbon is more electronegative due to greater percentage of s-character (50%).

39. Inter-electronic repulsion forces decrease sharply with increasing

✅ Correct Answer: (c)

Explanation:

✨ According to VSEPR theory, inter-electronic (electron–electron) repulsion depends mainly on the distance between electron pairs. When the bond angle increases, the distance between electron pairs increases. Greater separation means less repulsion, and this decrease is sharp and significant.

40. How many sigma bonds can be predicted between two atoms?

✅ Correct Answer: (c)

Explanation:

✨ Between any two atoms, only one sigma bond can form; additional bonds are Ï€ bonds.

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