Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment — NEET Chemistry MCQs with Solutions
Free NEET Chemistry Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment MCQs with step-by-step solutions (57 questions). Part of Chemical Bonding. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
Arrange the following compounds in increasing order of their dipole moment: HBr, H₂S, NF₃ and CHCl₃
A. NF₃ < HBr < H₂S < CHCl₃ ✓ Correct
B. CHCl₃ < NF₃ < HBr < H₂S
C. HBr < H₂S < NF₃ < CHCl₃
D. H₂S < HBr < NF₃ < CHCl₃
Solution: Experimental dipole moments: NF₃ ≈ 0.24 D (lone-pair moment opposes the N–F bond moments), HBr ≈ 0.79 D, H₂S ≈ 0.95 D, CHCl₃ ≈ 1.04 D. Hence NF₃ < HBr < H₂S < CHCl₃.
Q2 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Which one of the following molecules has maximum dipole moment?
A. NH₃ ✓ Correct
B. PF₅
C. CH₄
D. NF₃
Solution: PF₅ (trigonal bipyramidal) and CH₄ (tetrahedral) are symmetric with zero dipole moment. In NH₃ the lone-pair moment adds to the N–H bond moments (μ ≈ 1.47 D), while in NF₃ it opposes the N–F moments (μ ≈ 0.24 D). So NH₃ has the maximum dipole moment.
Q3 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
Arrange the bonds in order of increasing ionic character in the molecules: LiF, K₂O, N₂, SO₂ and ClF₃.
A. N₂ < SO₂ < ClF₃ < K₂O < LiF ✓ Correct
B. ClF₃ < N₂ < SO₂ < K₂O < LiF
C. LiF < K₂O < ClF₃ < SO₂ < N₂
D. N₂ < ClF₃ < SO₂ < K₂O < LiF
Solution: Ionic character increases with the electronegativity difference between the bonded atoms. N₂ (ΔEN = 0) is purely covalent; SO₂ and ClF₃ have small differences; K₂O and LiF are metal–nonmetal compounds with large differences, LiF being the most ionic. Order: N₂ < SO₂ < ClF₃ < K₂O < LiF (NCERT).
Q4 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Choose the polar molecule from the following.
A. CH₂=CH₂
B. CHCl₃ ✓ Correct
C. CCl₄
D. CO₂
Solution: CH₂=CH₂, CCl₄ and CO₂ are symmetric, so their bond moments cancel (μ = 0). In CHCl₃ the tetrahedral symmetry is broken (three C–Cl and one C–H), giving a net dipole moment (~1.04 D).
Q5 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Which of the following is least ionic?
A. CoCl₂
B. KCl
C. BaCl₂
D. AgCl ✓ Correct
Solution: By Fajan's rules, Ag⁺ has a pseudo noble-gas (18-electron) configuration, giving it much higher polarizing power than K⁺, Ba²⁺ or Co²⁺ of comparable charge. AgCl is therefore the most covalent, i.e. least ionic.
Q6 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
The pair from the following pairs having both compounds with net non-zero dipole moment is
A. 1,4-Dichlorobenzene, 1,3-Dichlorobenzene
B. Benzene, anisidine
C. CH₂Cl₂, CHCl₃ ✓ Correct
D. cis-butene, trans-butene
Solution: Both CH₂Cl₂ (~1.6 D) and CHCl₃ (~1.04 D) are polar. In the other pairs one member has zero dipole moment: 1,4-dichlorobenzene (para, moments cancel), benzene, and trans-2-butene.
Q7 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The carbonate ion CO₃²⁻ is represented by three resonance (canonical) structures. Which of the following is true?
A. All these structures are in dynamic equilibrium with each other.
B. Each structure exists for an equal amount of time.
C. CO₃²⁻ has a single structure, i.e. a resonance hybrid of the three structures. ✓ Correct
D. It is possible to identify each structure individually by some physical or chemical method.
Solution: Canonical structures have no real, independent existence — they are not in equilibrium and cannot be isolated or detected. The ion has one actual structure, the resonance hybrid, in which all three C–O bonds are identical.
Q8 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
Order of covalent character:
A. KF > KI ; LiF > KF
B. KF < KI ; LiF > KF
C. SnCl₄ > SnCl₂ ; CuCl > NaCl
D. LiF > KF ; CuCl < NaCl
E. KF < KI ; CuCl > NaCl
Choose the correct answer from the options given below
A. A, B only
B. B, C only
C. B, C, E only ✓ Correct
D. C, E only
Solution: By Fajan's rules: larger anion → more covalent, so KI > KF (B and E correct, A wrong); smaller cation → more covalent, so LiF > KF (B correct); higher cation charge → SnCl₄ > SnCl₂, and pseudo noble-gas Cu⁺ → CuCl > NaCl (C and E correct, D wrong). Hence B, C, E.
Q9 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Which of the following pairs of molecules contains an odd-electron molecule and an expanded-octet molecule?
A. BCl₃ and SF₆
B. NO and H₂SO₄ ✓ Correct
C. SF₆ and H₂SO₄
D. BCl₃ and NO
Solution: NO has 11 valence electrons (odd-electron molecule). In H₂SO₄ sulphur is surrounded by 12 electrons (expanded octet). BCl₃ is electron deficient (incomplete octet), and SF₆/H₂SO₄ are both expanded octets — neither of those pairs has an odd-electron member.
Q10 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The number of electron-deficient molecules among the following — PH₃, B₂H₆, CCl₄, NH₃, LiH and BCl₃ — is
A. 0
B. 1
C. 2 ✓ Correct
D. 3
Solution: B₂H₆ (banana 3c–2e bonds) and BCl₃ (boron has only 6 electrons) are electron deficient. PH₃, NH₃, CCl₄ have complete octets, and LiH is ionic — so the count is 2. (JEE Main 2022)
Q11 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
Identify the species having one π-bond and the maximum number of canonical forms from the following.
A. O₂
B. SO₃
C. CO₃²⁻ ✓ Correct
D. SO₂
Solution: CO₃²⁻ has one π-bond delocalized over three equivalent canonical structures. O₂ has no resonance, SO₂ has only two canonical forms, and SO₃ is conventionally drawn with more than one π-bond. (JEE Main 2021)
Q12 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The dipole moments of CCl₄, CHCl₃ and CH₄ are in the order
A. CH₄ = CCl₄ < CHCl₃ ✓ Correct
B. CHCl₃ < CH₄ = CCl₄
C. CH₄ < CCl₄ < CHCl₃
D. CCl₄ < CH₄ < CHCl₃
Solution: CH₄ and CCl₄ are perfectly tetrahedral, so their bond moments cancel and both have μ = 0. CHCl₃ is unsymmetrical and polar. Hence CH₄ = CCl₄ (= 0) < CHCl₃. (NEET 2020)
Q13 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Which of the following compounds contain(s) no covalent bond(s)?
KCl, PH₃, O₂, B₂H₆, H₂SO₄
A. KCl, B₂H₆, PH₃
B. KCl, H₂SO₄
C. KCl ✓ Correct
D. KCl, B₂H₆
Solution: PH₃, O₂, B₂H₆ and H₂SO₄ all contain covalent bonds. Only KCl is purely ionic (K⁺ and Cl⁻) with no covalent bond. (JEE Main 2018)
Q14 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
The intermolecular interaction that is dependent on the inverse cube of distance between the molecules is
A. London force
B. Hydrogen bond ✓ Correct
C. Ion–ion interaction
D. Ion–dipole interaction
Solution: A hydrogen bond is essentially a strong dipole–dipole interaction, whose energy varies as 1/r³. Ion–ion energy varies as 1/r, ion–dipole as 1/r², and London (dispersion) forces as 1/r⁶. (JEE Main 2020)
Q15 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
Molecule AB has a bond length of 1.617 Å and a dipole moment of 0.38 D. The fractional charge on each atom (absolute magnitude) is (e = 4.802 × 10⁻¹⁰ esu)
A. 0
B. 0.05 ✓ Correct
C. 0.5
D. 1.0
Solution: q = μ/d = (0.38 × 10⁻¹⁸ esu·cm)/(1.617 × 10⁻⁸ cm) ≈ 0.235 × 10⁻¹⁰ esu. Fractional charge = 0.235 × 10⁻¹⁰ / 4.802 × 10⁻¹⁰ ≈ 0.05.
Q16 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The correct statement for the molecule CsI₃ is
A. it contains Cs⁺, I⁻ and lattice I₂ molecules
B. it is a covalent molecule
C. it contains Cs⁺ and I₃⁻ ions ✓ Correct
D. it contains Cs³⁺ and I⁻ ions
Solution: CsI₃ is an ionic solid made of Cs⁺ cations and the linear triiodide anion I₃⁻. Cs shows only the +1 state, ruling out Cs³⁺. (JEE Main 2014)
Q17 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Among the following, the molecule with the lowest dipole moment is
A. CHCl₃
B. CH₃Cl
C. CH₂Cl₂
D. CCl₄ ✓ Correct
Solution: CCl₄ is a regular tetrahedron; the four C–Cl bond moments cancel exactly, giving μ = 0 — lower than CH₃Cl, CH₂Cl₂ or CHCl₃, which are all polar.
Q18 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Among the following, the maximum covalent character is shown by the compound
A. FeCl₂
B. SnCl₂
C. AlCl₃ ✓ Correct
D. MgCl₂
Solution: By Fajan's rules, covalent character increases with cation charge and decreasing cation size. Al³⁺ is small with a +3 charge, giving it the highest polarizing power among Fe²⁺, Sn²⁺ and Mg²⁺, so AlCl₃ is the most covalent. (AIEEE 2011)
Q19 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The charge/size ratio of a cation determines its polarizing power. Which one of the following sequences represents the increasing order of the polarizing power of the cationic species K⁺, Ca²⁺, Mg²⁺, Be²⁺?
A. Ca²⁺ < Mg²⁺ < Be²⁺ < K⁺
B. Mg²⁺ < Be²⁺ < K⁺ < Ca²⁺
C. Be²⁺ < K⁺ < Ca²⁺ < Mg²⁺
D. K⁺ < Ca²⁺ < Mg²⁺ < Be²⁺ ✓ Correct
Solution: Polarizing power ∝ charge/size. K⁺ has the lowest charge and large size; among the +2 ions size decreases Ca²⁺ > Mg²⁺ > Be²⁺. So polarizing power increases K⁺ < Ca²⁺ < Mg²⁺ < Be²⁺. (AIEEE 2007)
Q20 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
Among the following mixtures, dipole–dipole as the major interaction is present in
A. benzene and ethanol
B. acetonitrile and ethanol ✓ Correct
C. KCl and water
D. benzene and carbon tetrachloride
Solution: Acetonitrile and ethanol are both polar molecules, so dipole–dipole forces dominate between them. Benzene–ethanol is mainly dipole–induced dipole, KCl–water is ion–dipole, and benzene–CCl₄ (both non-polar) is dispersion only.
Q21 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
The correct order of increasing C–O bond length of CO, CO₃²⁻, CO₂ is
A. CO₃²⁻ < CO₂ < CO
B. CO₂ < CO₃²⁻ < CO
C. CO < CO₃²⁻ < CO₂
D. CO < CO₂ < CO₃²⁻ ✓ Correct
Solution: Bond length is inversely related to bond order. C–O bond orders: CO = 3, CO₂ = 2, CO₃²⁻ = 4/3 (resonance). So bond length increases CO < CO₂ < CO₃²⁻. (AIEEE)
Q22 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The number and type of bonds between the two carbon atoms in CaC₂ are
A. one sigma (σ) and one pi (π) bond
B. one sigma (σ) and two pi (π) bonds ✓ Correct
C. one sigma (σ) and one and a half pi (π) bonds
D. one sigma (σ) bond
Solution: Calcium carbide contains the acetylide ion C₂²⁻, which is isoelectronic with N₂ and has a C≡C triple bond: one σ and two π bonds.
Q23 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Which one is most ionic?
A. P₂O₅
B. CrO₃
C. MnO ✓ Correct
D. Mn₂O₇
Solution: By Fajan's rules, the lower the charge (oxidation state) of the cation, the more ionic the compound. Mn is +2 in MnO, versus +5 (P₂O₅), +6 (CrO₃) and +7 (Mn₂O₇), which are essentially covalent oxides. MnO is the most ionic.
Q24 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The molecule which has zero dipole moment is
A. CH₂Cl₂
B. BF₃ ✓ Correct
C. NF₃
D. ClO₂
Solution: BF₃ is trigonal planar; the three B–F bond moments at 120° cancel exactly, so μ = 0. CH₂Cl₂, NF₃ (pyramidal) and ClO₂ (bent) are all polar.
Q25 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The bond between two identical non-metal atoms has a pair of electrons
A. unequally shared between the two
B. transferred fully from one atom to another
C. with identical spins
D. equally shared between them ✓ Correct
Solution: Identical atoms have equal electronegativity, so the bonding pair is shared equally — a pure (non-polar) covalent bond. The shared electrons have opposite spins (Pauli principle).
Q26 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
Carbon tetrachloride has no net dipole moment because of
A. its planar structure
B. its regular tetrahedral structure ✓ Correct
C. similar sizes of carbon and chlorine
D. similar electron affinities of carbon and chlorine
Solution: Each C–Cl bond is polar, but in the regular tetrahedral geometry of CCl₄ the four bond moments are symmetrically arranged and cancel, giving zero net dipole moment.
Q27 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · medium
The types of bonds present in CuSO₄·5H₂O are only
A. electrovalent and covalent
B. electrovalent and coordinate covalent
C. electrovalent, covalent and coordinate covalent ✓ Correct
D. covalent and coordinate covalent
Solution: CuSO₄·5H₂O has electrovalent bonds between Cu²⁺ and SO₄²⁻, covalent bonds within SO₄²⁻ and in the O–H bonds of water, and coordinate bonds from the water molecules to Cu²⁺ (and in the hydrogen-bonded fifth water/sulphate linkage).
Q28 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The ion that is isoelectronic with CO is
A. CN⁻ ✓ Correct
B. O₂⁻
C. O₂⁺
D. N₂⁺
Solution: CO has 6 + 8 = 14 electrons. CN⁻ has 6 + 7 + 1 = 14 electrons — isoelectronic. O₂⁻ has 17, O₂⁺ has 15 and N₂⁺ has 13 electrons.
Q29 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
The compound with no dipole moment is
A. methyl chloride
B. carbon tetrachloride ✓ Correct
C. methylene chloride
D. chloroform
Solution: Carbon tetrachloride (CCl₄) is a regular tetrahedron, so its four C–Cl bond moments cancel and μ = 0. CH₃Cl, CH₂Cl₂ and CHCl₃ are all polar.
Q30 — Ionic and Covalent Bonding, Fajan's Rule and Dipole Moment · easy
If a molecule MX₃ has zero dipole moment, the sigma bonding orbitals used by M (atomic number < 21) are
A. pure p
B. sp hybrid
C. sp² hybrid ✓ Correct
D. sp³ hybrid
Solution: Zero dipole moment for MX₃ requires a symmetric trigonal planar geometry (like BF₃), which corresponds to sp² hybridization of M. A pyramidal sp³ MX₃ (like NH₃) would be polar.