NEET ChemistryUpdated 19 Oct 2026

Chemical Bonding and Molecular Structure: NEET PYQs and weightage

Chemical Bonding and Molecular Structure carries 9.2 of 100 Chemistry marks in NEET by past-paper share: 65 of the 707 tagged NEET Chemistry PYQs in the ViJEEta bank (NEET 2013–2026). It ranks 1 of 26 Chemistry chapters.

Take the 25-question Chemical Bonding and Molecular Structure test Key facts ↓All NEET Chemistry chapters

9.2/100 Weight in Chemistry

Exam importance (5/5, by past-paper share)

65 NEET PYQs

679 Practice questions

604 With measured difficulty

How the weight is computed: this chapter's tagged NEET PYQs divided by all tagged NEET Chemistry PYQs in the bank (65 of 707), times 100, with repeated questions counted once. The bank does not store the year of each NEET question, so none is printed. Computed from the bank at build time. Updated 19 Oct 2026.

Chemical Bonding and Molecular Structure: key facts for NEET

16 facts the paper keeps asking, each with how it is asked. Copy it onto one page of your notebook: that page is this chapter's handbook.

Octet rule (Kössel–Lewis)
Atoms bond by transferring or sharing valence electrons to reach eight in the valence shell; $He$ is stable with a duplet.
Asked as: Which statement about the Kössel–Lewis electronic theory of bonding is correct?
Octet exceptions
Incomplete octet ( $LiCl$ , $Be H_{2}$ , $BC l_{3}$ , $AlC l_{3}$ , $B F_{3}$ ), odd-electron ( $NO$ , $N O_{2}$ ), expanded octet ( $P F_{5}$ , $S F_{6}$ , $H_{2} S O_{4}$ ); $SC l_{2}$ obeys the octet.
Asked as: Which molecule does NOT obey the octet rule / which has an expanded octet?
Formal charge
$Formal charge = valence e^{-} (free atom) - lone-pair e^{-} - \frac{1}{2} bonding e^{-}$
In $O_{3}$ the central O is $+ 1$ and the singly bonded end O is $- 1$ .
Asked as: Formal charge on the central O of $O_{3}$ ; the most stable Lewis structure has the smallest formal charges.
Stability of ionic compounds
Stability of an ionic compound is measured by its lattice enthalpy, not by octet formation; ionisation is always endothermic, electron gain can be either.
Asked as: Why does $NaCl$ form even though $IE + Δ_{e g} H$ is positive?
Covalent vs van der Waals radius
Covalent radius = half the distance between two bonded like atoms; van der Waals radius = half the distance between like atoms of separate molecules ( $Cl$ : $99 pm$ vs $180 pm$ ).
Asked as: Compare the covalent and van der Waals radius of $Cl$ , or which one is larger.
Bond enthalpy
$H - H$ $435.8$ , $O = O$ $498$ , $N \equiv N$ $946.0 kJ mo l^{- 1}$ ; for polyatomics such as $H_{2} O$ , use the average bond enthalpy.
Asked as: Arrange the bonds by strength; why the two $O - H$ bonds of $H_{2} O$ need different energies to break.
Isoelectronic species and bond order
Isoelectronic species have equal bond order: $F_{2}$ and $O_{2}^{2 -}$ $= 1$ ; $N_{2}$ , $CO$ , $N O^{+}$ $= 3$ . Higher bond order means higher bond enthalpy and shorter bond length.
Asked as: Pick the pair with the same bond order / arrange by bond length.
Resonance
The canonical forms have no real existence, and the hybrid is lower in energy than any single form; $O_{3}$ , $C O_{3}^{2 -}$ and $C O_{2}$ have equal, averaged bonds.
Asked as: Which statement about resonance is incorrect (e.g. "the molecule oscillates between forms")?
Dipole moment
$μ = charge \times distance (in debye)$
$Be F_{2}$ , $B F_{3}$ , $C O_{2}$ , $C H_{4}$ and $CC l_{4}$ have zero dipole; $H_{2} O = 1.85 D$ . $N H_{3} > N F_{3}$ because the lone-pair dipole opposes the $N - F$ bond dipoles.
Asked as: Which has zero dipole moment, and why is $μ (N H_{3}) > μ (N F_{3})$ ?
Fajans' rules
Covalent character rises with a smaller cation, a larger anion and a higher cation charge; for cations of the same size and charge, an $(n - 1) d^{n} n s^{0}$ (transition-metal) cation polarises more than one with a noble-gas $n s^{2} n p^{6}$ configuration.
Asked as: Arrange halides/salts by increasing covalent character.
VSEPR repulsion order
$lp-lp > lp-bp > bp-bp$
A lone pair sits equatorial in $S F_{4}$ (see-saw), and $Cl F_{3}$ ( $2$ lp) is T-shaped.
Asked as: Why is the $H_{2} O$ bond angle less than $N H_{3}$ (both from $109. 5^{\circ}$ ); shape of $S F_{4}$ or $Cl F_{3}$ .
σ and π bonds
$triple bond = 1 σ + 2 π$
A $σ$ bond (axial overlap) is stronger than a $π$ bond (sidewise overlap); a $π$ bond forms only in addition to $σ$ .
Asked as: Count the $σ$ and $π$ bonds in $C_{2} H_{2}$ or $C_{2} H_{4}$ ; which overlap cannot form a $σ$ bond.
Hybridisation
$s p$ ( $50%$ s, $18 0^{\circ}$ , $BeC l_{2}$ ), $s p^{2}$ ( $12 0^{\circ}$ , $BC l_{3}$ ), $s p^{3}$ ( $25%$ s, $109. 5^{\circ}$ , $C H_{4}$ ). The number of hybrids equals the number of orbitals mixed; promotion is not essential, and filled orbitals can take part.
Asked as: Hybridisation of each C in $C H_{2} = CH - C \equiv CH$ ; which statement about hybridisation is false.
Expanded hybridisations and shapes
$PC l_{5}$ is $s p^{3} d$ (trigonal bipyramidal), and its axial bonds are longer and weaker than its equatorial bonds. $S F_{6}$ is $s p^{3} d^{2}$ (octahedral), $Br F_{5}$ is $s p^{3} d^{2}$ (square pyramidal), and $[Ni (CN)_{4}]^{2 -}$ and $[PtC l_{4}]^{2 -}$ are $d s p^{2}$ (square planar).
Asked as: Why axial $P - Cl$ bonds are longer; match each species to its hybridisation and shape.
MO bond order
$Bond order = \frac{1}{2} (N_{b} - N_{a})$
$H e_{2}$ and $B e_{2}$ have bond order $0$ and do not exist; $L i_{2}$ has bond order $1$ and is diamagnetic; $C_{2}$ 's double bond is both $π$ ; $O_{2}$ has bond order $2$ and is paramagnetic with $2$ unpaired $e^{-}$ .
Asked as: Bond order and magnetic nature of $O_{2}$ , $O_{2}^{+}$ , $O_{2}^{-}$ , $O_{2}^{2 -}$ or $N_{2}$ ; which species does not exist.
Hydrogen bonding
Hydrogen bonds form only with $F$ , $O$ or $N$ . They are intermolecular ( $HF$ , water, alcohol) or intramolecular (o-nitrophenol), and are strongest in the solid state and weakest in the gas.
Asked as: Which compound shows intramolecular H-bonding / why $HF$ is associated.

Trap

The MO energy order switches between N₂ and O₂. For B₂, C₂ and N₂, π2p lies below σ2pz. For O₂ and F₂, σ2pz lies below π2p. Using the wrong order gives the wrong magnetic nature (e.g. B₂, C₂); the bond order comes out the same either way.

How does NEET ask Chemical Bonding and Molecular Structure?

8 real previous-year questions from this chapter, as printed in the paper, each with its worked solution. Answer the first one here with no sign-in.

Q1ChemistryNEET UG PYQVSEPR Theory

Try right here · No sign-in

Predicted the correct order of repulsion among the following :

Answer key (B) & worked solution

Correct answer: Option B

The order of repulsion force according to VSEPR theory : lone pair-lone pair > lone pair-bond pair > bond pair – bond pair

Q2ChemistryNEET UG PYQMolecular Orbital Theory

Which of the following diatomic molecular species has only π bonds according to Molecular Orbital Theory ?

N_{2}

C_{2}

B e_{2}

O_{2}

Answer key (B) & worked solution

Correct answer: Option B

MO configuration C

_{2}

is :

σ 1 s^{2}, σ * 1 s^{2}, σ 2 s^{2}, σ * 2 s^{2}, π 2 p_{x}^{2} = π 2 p_{y}^{2}

Q3ChemistryNEET UG PYQElectrovalent or Ionic Bond

The ionic radii of A

^{+}

and B

^{-}

ions are 0.98 × 10−10m and 1.81 × 10−10 m. The coordination number of each ion in AB is:

Answer key (B) & worked solution

Correct answer: Option B

\frac{r _{A +}}{r _{B +}} = \frac{0.98 \times 10 ^{- 10}}{1.81 \times 10 ^{- 10}} = 0.54

\frac{r ^{+}}{r ^{-}}

is in range 0.414 – 0.732 so octahedral. Co-ordination no. of each ion is 6 like NaCl structure.

Q4ChemistryNEET UG PYQElectrovalent or Ionic Bond

Magnesium reacts with an element (X) to form an ionic compound. If the ground state electronic configuration of (X) is 1s

^{2}

^{2}

^{3}

, the simplest formula for this compound is

AMg

_{2}

BMgX

_{2}

CMg

_{2}

_{3}

DMg

_{3}

_{2}

Answer key (D) & worked solution

Correct answer: Option D

Element (X) electronic configuration 1s

^{2}

^{2}

^{3}

So, valency of X will be 3. Valency of Mg is 2. Formula of compound formed by Mg and X will be Mg

_{3}

_{2}

Q5ChemistryNEET UG PYQVSEPR Theory

Amongst the following which one will have maximum 'lone pair- lone pair' electron repulsions?

AClF

_{3}

BIF

_{5}

CSF

_{4}

DXeF

_{2}

Answer key (D) & worked solution

Correct answer: Option D

XeF

_{2}

has two bond pair and three lone pair that gives it maximum lone pair-lone pair repulsion.

Q6ChemistryNEET UG PYQBond Parameters

Identify the correct orders against the property mentioned A. H

_{2}

O > NH

_{3}

> CHCl

_{3}

– dipole moment B. XeF

_{4}

> XeO

_{3}

> XeF

_{2}

– number of lone pairs on central atom C. O–H > C–H > N–O – bond length D. N

_{2}

> O

_{2}

> H

_{2}

– bond enthalpy Choose the answer from the options given below :

AA, C only

BB, C only

CA, D only

DB, D only

Answer key (C) & worked solution

Correct answer: Option C

_{2}

O > NH

_{3}

> CHCl

_{3}

– dipole moment N

_{2}

> O

_{2}

> H

_{2}

– bond enthalpy

Q7ChemistryNEET UG PYQMolecular Orbital Theory

which of the following is paramagnetic?

ACO

O_{2}^{-}

CCN

^{-}

DNO

^{+}

Answer key (B) & worked solution

Correct answer: Option B

O_{2}^{-}

contains one unpaired electron and hence is paramagnetic.

Q8ChemistryNEET UG PYQVSEPR Theory

Match List-I with List-II List-IList-IIA. XeO

_{3}

I. sp

^{3}

d; linearB. XeF

_{2}

II. sp

^{3}

; pyramidalC. XeOF

_{4}

III. sp

^{3}

^{3}

; distorted octahedralD. XeF

_{6}

IV. sp

^{3}

^{2}

; square pyramidal Choose the correct answer from the options given below:

AA-IV, B-II, C-III, D-I

BA-IV, B-II, C-I, D-III

CA-II, B-I, C-IV, D-III

DA-II, B-I, C-III, D-IV

Answer key (C) & worked solution

Correct answer: Option C

A-II, B-I, C-IV, D-III

Which topics in Chemical Bonding and Molecular Structure carry the most questions?

The 12 busiest of 20 topics, by tagged PYQs, then practice questions. Counted from the bank. Updated 19 Oct 2026.

Topic	PYQs	Practice questions
VSEPR Theory	18	119
Molecular Orbital Theory	10	103
Hybridisation	6	115
Dipole Moment of a Bond	4	56
Valence Bond Theory	4	29
Electrovalent or Ionic Bond	4	25
Kossel and Lewis Approach	3	18
Covalent Bond	3	17
Metallic Bond	3	3
Bond Parameters	2	25
Intermolecular Forces	2	7
Hydrogen Bonding	1	52

Why does Chemical Bonding and Molecular Structure show "–" until you answer 3 questions?

Unknown is not zero. Until you answer at least 3 graded questions in Chemical Bonding and Molecular Structure, ViJEEta shows – instead of a zero or a 50% default. Book exercises can raise chapter mastery up to 0.60, adaptive practice up to 0.75, and only a timed chapter test or mock can certify 0.80 and above.

How ViJEEta scores you

What happens when you test Chemical Bonding and Molecular Structure?

Every chapter test is 25 questions. It starts at moderate difficulty and adapts after each saved answer. If you open a solution before answering, that attempt earns no credit, so your mastery stays honest.

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Chapters either side of Chemical Bonding and Molecular Structure by weight

Coordination Compounds Weight 6.5/100 Hydrocarbons Weight 5.9/100

Chemical Bonding and Molecular Structure: NEET PYQs and weightage

Chemical Bonding and Molecular Structure: key facts for NEET

Octet rule (Kössel–Lewis)

Octet exceptions

Formal charge

Stability of ionic compounds

Covalent vs van der Waals radius

Bond enthalpy

Isoelectronic species and bond order

Resonance

Dipole moment

Fajans' rules

VSEPR repulsion order

σ and π bonds

Hybridisation

Expanded hybridisations and shapes

MO bond order

Hydrogen bonding

How does NEET ask Chemical Bonding and Molecular Structure?

Which topics in Chemical Bonding and Molecular Structure carry the most questions?

Why does Chemical Bonding and Molecular Structure show "–" until you answer 3 questions?

What happens when you test Chemical Bonding and Molecular Structure?

Chapters either side of Chemical Bonding and Molecular Structure by weight