Chemical Bonding and Molecular Structure NEET PYQReal NEET & AIPMT 2005–2021 questions, year-tagged, with solutions
By the RankUp team, founded by Dr. Deepak Sahu (MBBS Gold Medalist, NEET PG AIR 1731) · Updated
Every Chemical Bonding and Molecular Structure question from the NEET & AIPMT papers on this site (2005–2021), newest first. Each is tagged with its paper. Tap an option to check your answer and read the explanation.
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Chemical Bonding and Molecular Structure previous year questions
68 questions. Tap an option to check your answer.
Q1NEET 2021
BF₃ is planar and electron deficient compound. Hybridization and number of electrons around the central atom, respectively are :
Not quite — the answer is C.
Boron in BF₃ forms three σ bonds and has no lone pair, so it is sp² hybridised and trigonal planar. It has only 6 electrons in its valence shell, which is why it is electron deficient; 8 would complete the octet.
Q2NEET 2021
Match List - I with List - II. List - I | List - II (a) PCl₅ | (i) Square pyramidal (b) SF₆ | (ii) Trigonal planar (c) BrF₅ | (iii) Octahedral (d) BF₃ | (iv) Trigonal bipyramidal Choose the correct answer from the options given below.
Not quite — the answer is A.
PCl₅: 5 bond pairs, trigonal bipyramidal. SF₆: 6 bond pairs, octahedral. BrF₅: 5 bond pairs + 1 lone pair, square pyramidal. BF₃: 3 bond pairs, trigonal planar.
Q3NEET 2021
Which of the following molecules is non-polar in nature ?
Not quite — the answer is C.
SbCl₅ is trigonal bipyramidal with five identical Sb–Cl bonds, so the bond dipoles cancel and the molecule is non-polar. POCl₃ (unequal P=O and P–Cl bonds), CH₂O (trigonal planar with C=O) and bent NO₂ all have net dipoles.
Q4NEET 2020 · Q91
Identify a molecule which does not exist.
Not quite — the answer is A.
He₂ would have the configuration σ1s² σ*1s², so its bond order is (2 − 2)/2 = 0 and no stable molecule forms. Li₂, C₂ and O₂ all have positive bond orders (1, 2 and 2), so they exist.
Q5NEET 2020 · Q98
Which of the following set of molecules will have zero dipole moment ?
Not quite — the answer is D.
BF₃ (trigonal planar), BeF₂ and CO₂ (linear) and 1,4-dichlorobenzene (para-substituted) are symmetric, so their bond dipoles cancel. Ammonia, water, NF₃, HF and 1,3-dichlorobenzene all have a net dipole, so every other set contains at least one polar molecule.
Q6NEET 2019 · Q59
Which of the following diatomic molecular species has only π bonds according to Molecular Orbital Theory?
Not quite — the answer is C.
C₂ (12 electrons) has configuration σ1s² σ*1s² σ2s² σ*2s² (π2pₓ² = π2p_y²); its bond order of 2 comes from the two π bonding pairs only, with no σ2p electrons. N₂ and O₂ contain a σ2p bond in addition to π bonds, and Be₂ has no net bond.
Q7NEET 2018 · Q51
In the structure of ClF₃, the number of lone pairs of electrons on central atom 'Cl' is
Not quite — the answer is B.
Cl has 7 valence electrons; 3 form bonds with F, leaving 4 electrons = 2 lone pairs. Five electron pairs give a trigonal bipyramidal arrangement with the two lone pairs equatorial, hence the T-shape.
Q8NEET 2018 · Q87
Consider the following species: CN⁺, CN⁻, NO and CN. Which one of these will have the highest bond order?
Not quite — the answer is B.
By MO theory: CN⁻ (14 electrons) has bond order 3; CN (13) and NO (15) have 2.5; CN⁺ (12) has 2. So CN⁻ has the highest bond order; removing an electron from CN lowers it.
Q9NEET 2018 · Q88
Magnesium reacts with an element (X) to form an ionic compound. If the ground state electronic configuration of (X) is 1s² 2s² 2p³, the simplest formula for this compound is
Not quite — the answer is D.
X is nitrogen, which gains 3 electrons to form N³⁻, while Mg forms Mg²⁺. Charge balance requires 3 Mg²⁺ for 2 N³⁻, giving Mg₃X₂ (magnesium nitride). Mg₂X₃ reverses the subscripts.
Q10NEET 2017 · Q4
Which of the following pairs of compounds is isoelectronic and isostructural?
Not quite — the answer is C.
XeF₂ and IBr₂⁻ both have 22 valence electrons (8 + 14 and 7 + 14 + 1) and both have three lone pairs on the central atom with two bonds, giving a linear shape. BeCl₂ is linear but has only 16 valence electrons, and TeI₂ is bent.
Q11NEET 2017 · Q5
The species, having bond angles of 120° is:
Not quite — the answer is D.
BCl₃ has sp² boron with no lone pair, so it is trigonal planar with 120° angles. PH₃ and NCl₃ are pyramidal (angles below 109.5°) and ClF₃ is T-shaped (angles near 90°).
Q12NEET 2017 · Q7
Which one of the following pairs of species have the same bond order?
Not quite — the answer is C.
CN⁻ and CO are both 14-electron species, isoelectronic with N₂, so each has bond order 3. NO has 2.5 against 3 for CO, O₂ has 2 against 3 for NO⁺, and O₂⁻ has 1.5 against 3 for N₂.
Q13NEET 2017 (Gujarati paper) · Q13
Which of the following hydrides has the largest bond angle?
Not quite — the answer is C.
Oxygen is the smallest and most electronegative central atom, so the bonding pairs sit close to it and repel strongly, keeping the angle near 104.5°. Down the group the bonding pairs move away and the angle falls towards 90° (H₂S about 92°, H₂Te about 90°).
Q14NEET 2017 (Gujarati paper) · Q42
Which of the following pair of species is not iso-structural?
Not quite — the answer is B.
ClO₃⁻ has three bond pairs and one lone pair on Cl (sp³), so it is trigonal pyramidal, whereas CO₃²⁻ is sp² trigonal planar. ICl₄⁻ and XeF₄ are both square planar, IBr₂⁻ and XeF₂ both linear, and BrO₃⁻ and XeO₃ both pyramidal.
Q15NEET 2016 Phase 2 · Q65
The hybridizations of atomic orbitals of nitrogen in NO₂⁺, NO₃⁻ and NH₄⁺ respectively are
Not quite — the answer is C.
NO₂⁺ is linear with two σ bonds and no lone pair on N (sp). NO₃⁻ is trigonal planar with three σ bonds (sp²). NH₄⁺ is tetrahedral with four σ bonds (sp³). So the sequence is sp, sp², sp³.
Q16NEET 2016 Phase 2 · Q71
The correct geometry and hybridization for XeF₄ are
Not quite — the answer is D.
Xe in XeF₄ has 4 bond pairs and 2 lone pairs, six electron pairs in all, so it is sp³d² hybridised. The electron-pair arrangement is octahedral, but with the two lone pairs opposite each other the shape of the molecule is square planar.
Q17NEET 2016 Phase 1 · Q46
Consider the molecules CH₄, NH₃ and H₂O. Which of the given statements is false?
Not quite — the answer is B.
All three are sp³ hybridised, with bond angles CH₄ 109.5° > NH₃ 107° > H₂O 104.5°, because lone pairs repel bonding pairs more strongly. So the claim that water's angle exceeds methane's is false; all three angles are still above 90°.
Q18NEET 2016 Phase 1 · Q70
Predict the correct order among the following:
Not quite — the answer is A.
According to VSEPR theory, lone pairs are held only by one nucleus and spread out more, so they repel most strongly. The repulsion order is lone pair–lone pair > lone pair–bond pair > bond pair–bond pair, which is why lone pairs compress bond angles in NH₃ and H₂O.
Q19NEET 2016 Phase 1 · Q73
Match the compounds given in column I with the hybridisation and shape given in column II and mark the correct option. Column I: (a) XeF₆, (b) XeO₃, (c) XeOF₄, (d) XeF₄ Column II: (i) distorted octahedral, (ii) square planar, (iii) pyramidal, (iv) square pyramidal
Not quite — the answer is A.
XeF₆ (sp³d³, 6 bond pairs + 1 lone pair) is distorted octahedral; XeO₃ (sp³, 3 bond pairs + 1 lone pair) is pyramidal; XeOF₄ (sp³d², 5 bond pairs + 1 lone pair) is square pyramidal; XeF₄ (sp³d², 4 bond pairs + 2 lone pairs) is square planar. A square planar XeO₃ is impossible because its lone pair makes it pyramidal.
Q20AIPMT 2015
The enolic form of ethyl acetoacetate, CH₃–C(OH)=CH–COOC₂H₅ (in equilibrium with the keto form CH₃–CO–CH₂–COOC₂H₅), has:
Not quite — the answer is B.
CH₃–C(OH)=CH–COOC₂H₅ has 9 C–H, 4 C–C, 4 C–O and 1 O–H σ bonds = 18 σ bonds, and two π bonds (one C=C, one C=O). 9 σ bonds counts only the skeleton without hydrogens.
Q21AIPMT 2015
Which of the following species contain equal number of σ- and π-bonds?
Not quite — the answer is C.
XeO₄ has four Xe–O σ bonds and four π bonds (each Xe=O is one σ + one π). CH₂(CN)₂ has 6 σ and 4 π, (CN)₂ has 3 σ and 4 π, and HCO₃⁻ has 4 σ and 1 π.
Q22AIPMT 2015
The correct bond order in the following species is:
Not quite — the answer is A.
By MO theory O₂ has bond order 2; removing antibonding electrons raises it: O₂⁺ = 2.5, O₂²⁺ = 3, while adding one gives O₂⁻ = 1.5. So O₂⁻ < O₂⁺ < O₂²⁺.
Q23AIPMT 2015
Which of the following pairs of ions are isoelectronic and isostructural?
Not quite — the answer is A.
ClO₃⁻ (17 + 24 + 1 = 42 electrons) and SO₃²⁻ (16 + 24 + 2 = 42) are isoelectronic, and both have three bond pairs and one lone pair, so both are pyramidal. CO₃²⁻ and NO₃⁻ are trigonal planar with 32 electrons.
Q24AIPMT 2015
Which of the following options represents the correct bond order?
Not quite — the answer is C.
MO bond orders: O₂⁻ = 1.5, O₂ = 2, O₂⁺ = 2.5, because electrons are added to or removed from the π* antibonding orbitals. Hence O₂⁻ < O₂ < O₂⁺.
Q25AIPMT 2015
Maximum bond angle at nitrogen is present in which of the following?
Not quite — the answer is D.
NO₂⁺ is isoelectronic with CO₂ and is linear (180°). NO₃⁻ is trigonal planar (120°), NO₂ is bent (~134°) and NO₂⁻ is bent (~115°) due to the lone pair.
Q26AIPMT 2014
Which of the following organic compounds has same hybridization as its combustion product (CO₂)?
Not quite — the answer is A.
Carbon in CO₂ is sp hybridised. Ethyne carbons are also sp, whereas ethene carbons are sp² and ethane/ethanol carbons are sp³.
Q27AIPMT 2014
Which one of the following species has plane triangular shape?
Not quite — the answer is A.
In NO₃⁻ the nitrogen has three bond pairs and no lone pair (sp²), giving a trigonal planar shape. NO₂⁻ has a lone pair and is bent, while CO₂ and N₃⁻ are linear.
Q28AIPMT 2014
Which of the following molecules has the maximum dipole moment?
Not quite — the answer is B.
In NH₃ the lone-pair moment and the N–H bond moments point the same way, giving about 1.47 D. In NF₃ the N–F bond moments oppose the lone pair (about 0.23 D), and CH₄ and CO₂ are non-polar.
Q29NEET 2013
Which of the following is paramagnetic ?
Not quite — the answer is B.
CO, CN⁻ and NO⁺ are isoelectronic with 14 electrons and have all electrons paired. O₂⁻ has 17 electrons, with one unpaired electron in a π* orbital, so it is paramagnetic.
Q30NEET 2013
XeF₂ is isostructural with
Not quite — the answer is B.
XeF₂ has 5 electron pairs (2 bond pairs, 3 lone pairs), sp³d, and is linear. ICl₂⁻ also has 2 bond pairs and 3 lone pairs, so it is linear too. TeF₂ is bent and SbCl₃ is pyramidal; BaCl₂ is an ionic solid.
Q31NEET 2013
Which of the following is electron-deficient?
Not quite — the answer is C.
(BH₃)₂ is diborane, B₂H₆. Each boron has only three valence electrons, so the molecule lacks enough electrons for normal two-electron bonds and uses 3-centre-2-electron B–H–B bonds: it is electron deficient. Ethane, disilane and PH₃ have complete octets.
Q32NEET 2013
Which one of the following molecules contains no π bond?
Not quite — the answer is B.
H₂O has only two O–H σ bonds. CO₂ (O=C=O), SO₂ and NO₂ all contain double-bond character and so π bonds.
Q33NEET 2013
Which of the following is a polar molecule ?
Not quite — the answer is B.
SF₄ has four bond pairs and one lone pair (see-saw shape), so its bond dipoles do not cancel and it is polar. BF₃ (trigonal planar), SiF₄ (tetrahedral) and XeF₄ (square planar) are symmetric, so they are non-polar.
Q34AIPMT 2012 Mains
During change of O₂ to O₂⁻ ion, the electron adds on which one of the following orbitals?
Not quite — the answer is A.
In O₂ the two π*2p orbitals each hold one electron, and they are the lowest vacant-capacity orbitals, so the extra electron of O₂⁻ enters a π* orbital. The bonding π and σ orbitals are already full.
Q35AIPMT 2012 Mains
Four diatomic species are listed below. Identify the correct order in which the bond order is increasing in them:
Not quite — the answer is D.
Bond orders from MO theory: He₂⁺ = 0.5, O₂⁻ = 1.5, NO = 2.5 and C₂²⁻ = 3 (isoelectronic with N₂). So the increasing order is He₂⁺ < O₂⁻ < NO < C₂²⁻.
Q36AIPMT 2012 Prelims
Which one of the following pairs is isostructural (i.e. having the same shape and hybridization)?
Not quite — the answer is A.
In BF₄⁻ and NH₄⁺ the central atom has four bond pairs and no lone pair: sp³, tetrahedral. BCl₃ is trigonal planar while BrCl₃ is T-shaped; NH₃ is pyramidal while NO₃⁻ is trigonal planar; NF₃ is pyramidal while BF₃ is planar.
Q37AIPMT 2012 Prelims
Bond order of 1.5 is shown by:
Not quite — the answer is C.
By MO theory, O₂⁻ has 10 bonding and 7 antibonding electrons (valence), bond order = (10 − 7)/2 = 1.5. O₂ is 2, O₂⁺ is 2.5 and O₂²⁻ is 1.
Q38AIPMT 2012 Prelims
The pair of species with the same bond order is
Not quite — the answer is B.
O₂²⁻ (18 electrons) has bond order 1 and B₂ (10 electrons) also has bond order 1. N₂ = 3 vs O₂ = 2; O₂⁺ = 2.5 vs NO⁺ = 3; NO = 2.5 vs CO = 3.
Q39AIPMT 2012 Prelims
Which of the following species contains three bond pairs and one lone pair around the central atom?
Not quite — the answer is A.
P in PCl₃ has 5 valence electrons: three form bonds with Cl and two remain as one lone pair (pyramidal). H₂O and NH₂⁻ each have two bond pairs and two lone pairs, and BF₃ has three bond pairs and no lone pair.
Q40AIPMT 2011 Mains
The pairs of species of oxygen and their magnetic behaviours are noted below. Which of the following presents the correct description?
Not quite — the answer is A.
By MO theory O₂ has 2 unpaired electrons and O₂⁺ has 1, so both are paramagnetic. O₂²⁻ has all electrons paired (diamagnetic), so the pairings with peroxide as paramagnetic are wrong, and O₂⁻ has 1 unpaired electron, so calling it diamagnetic is wrong.
Q41AIPMT 2011 Prelims
The correct order of increasing bond length of C–H, C–O, C–C and C=C is
Not quite — the answer is B.
Typical bond lengths: C–H ≈ 109 pm, C=C ≈ 134 pm, C–O ≈ 143 pm, C–C ≈ 154 pm. So the increasing order is C–H < C=C < C–O < C–C. A double bond is shorter than any of the carbon single bonds to C or O.
Q42AIPMT 2011 Prelims
Which of the following is least likely to behave as Lewis base?
Not quite — the answer is D.
A Lewis base donates an electron pair. OH⁻, H₂O and NH₃ all have lone pairs, whereas BF₃ has an incomplete octet on boron and accepts a pair, so it is a Lewis acid and least likely to act as a base.
Q43AIPMT 2011 Prelims
Which of the following has the minimum bond length?
Not quite — the answer is B.
MO bond orders: O₂⁺ 2.5, O₂ 2, O₂⁻ 1.5, O₂²⁻ 1. Bond length decreases as bond order increases, so O₂⁺ has the shortest bond. Adding electrons fills π* orbitals and lengthens the bond.
Q44AIPMT 2010 Mains · Q102
In which of the following molecules the central atom does not have sp3 hybridization?
Not quite — the answer is B.
SF₄ has 4 bond pairs and 1 lone pair on S (5 electron pairs), so S is sp³d with a see-saw shape. CH₄, BF₄⁻ and NH₄⁺ all have four electron pairs and are sp³.
Q45AIPMT 2010 Mains · Q116
Some of the properties of the two species, NO₃⁻ and H₃O⁺ are described below. Which one of them is correct?
Not quite — the answer is A.
In NO₃⁻ nitrogen has three σ-bonds and no lone pair, so it is sp² and trigonal planar. In H₃O⁺ oxygen has three bonds and one lone pair, so it is sp³ and pyramidal. Thus both the hybridization and the shapes differ; they are not isostructural.
Q46AIPMT 2010 Prelims · Q62
Which one of the following species does not exist under normal conditions?
Not quite — the answer is C.
Be₂ has 8 electrons: σ1s² σ*1s² σ2s² σ*2s², bond order (4 − 4)/2 = 0, so it does not exist. Li₂ (bond order 1), Be₂⁺ (bond order ½) and B₂ (bond order 1) have positive bond orders.
Q47AIPMT 2010 Prelims · Q71
In which of the following pairs of molecules/ions, the central atoms have sp² hybridization?
Not quite — the answer is C.
BF₃ has 3 bond pairs and no lone pair (sp²); NO₂⁻ has 2 bond pairs and 1 lone pair on N (sp²). NH₂⁻, NH₃ and H₂O each have 4 electron pairs on the central atom and are sp³.
Q48AIPMT 2010 Prelims · Q81
In which one of the following species the central atom has the type of hybridisation which is not the same as that present in the other three?
Not quite — the answer is D.
PCl₅ (5 bond pairs), SF₄ (4 bp + 1 lp) and I₃⁻ (2 bp + 3 lp) all have 5 electron pairs: sp³d. SbCl₅²⁻ has Sb(III) with 5 bond pairs and 1 lone pair, 6 pairs: sp³d², so it is the odd one out.
Q49AIPMT 2010 Prelims · Q82
Which of the following molecular hydrides acts as a Lewis acid?
Not quite — the answer is D.
B₂H₆ is electron-deficient (each B has an incomplete octet) and accepts electron pairs, so it acts as a Lewis acid. CH₄ is electron-precise, while NH₃ and H₂O have lone pairs and act as Lewis bases.
Q50AIPMT 2009 Prelims · Q165
What is the dominant intermolecular force or bond that must be overcome in converting liquid CH₃OH to a gas?
Not quite — the answer is D.
Methanol molecules are linked by O–H···O hydrogen bonds, which are the dominant forces to be overcome on boiling. Covalent bonds are broken only in a chemical change, and dipole–dipole and London forces are present but weaker.
Q51AIPMT 2009 Prelims · Q180
According to MO theory which of the following lists ranks the nitrogen species in terms of increasing bond order?
Not quite — the answer is A.
N₂ (14 electrons) has bond order 3. Each extra electron enters an antibonding π* orbital and lowers the bond order by ½: N₂⁻ = 2.5, N₂²⁻ = 2. Increasing order: N₂²⁻ < N₂⁻ < N₂.
Q52AIPMT 2009 Prelims · Q194
In which of the following molecules / ions BF₃, NO₂⁻, NH₂⁻ and H₂O, the central atom is sp² hybridized?
Not quite — the answer is C.
BF₃ has three bond pairs and no lone pair, and NO₂⁻ has two σ bonds and one lone pair on N; both have three electron domains, so sp². NH₂⁻ and H₂O each have two bond pairs and two lone pairs (four domains), so they are sp³.
Q53AIPMT 2008 Prelims · Q81
The angular shape of ozone molecule (O₃) consists of
Not quite — the answer is A.
Ozone has two O–O σ bonds forming the bent skeleton, and one π bond that is delocalised over the three atoms by resonance (each O–O has bond order 1.5). Two π bonds would require one O=O on each side, which is not the structure.
Q54AIPMT 2008 Prelims · Q82
The correct order of increasing bond angles in the following triatomic species is
Not quite — the answer is C.
NO₂⁺ has no non-bonding electrons on N and is linear (180°). NO₂ has a single unpaired electron on N (about 134°), and NO₂⁻ has a full lone pair that repels more strongly (about 115°). So the increasing order is NO₂⁻ < NO₂ < NO₂⁺. The reverse order wrongly treats the linear cation as the most bent.
Q55AIPMT 2008 Prelims · Q83
Four diatomic species are listed below in different sequences. Which of these presents the correct order of their increasing bond order?
Not quite — the answer is A.
From MO theory: He₂⁺ (3 e⁻) has bond order 0.5, O₂⁻ (17 e⁻) 1.5, NO (15 e⁻) 2.5, and C₂²⁻ (14 e⁻, like N₂) 3. The increasing order is He₂⁺ < O₂⁻ < NO < C₂²⁻. Placing He₂⁺ last mistakes its weak half bond for a strong one.
Q56AIPMT 2007 Prelims · Q59
In which of the following pairs, the two species are iso-structure?
Not quite — the answer is C.
BrO₃⁻ and XeO₃ each have three bond pairs and one lone pair on the central atom, so both are trigonal pyramidal. SO₃²⁻ is pyramidal but NO₃⁻ is planar; BF₃ is planar but NF₃ pyramidal; SF₄ is see-saw but XeF₄ square planar.
Q57AIPMT 2007 Prelims · Q85
The correct order of C–O bond length among CO, CO₃²⁻, CO₂ is
Not quite — the answer is C.
C–O bond order is about 3 in CO, 2 in CO₂ and 1⅓ in CO₃²⁻ (resonance). Higher bond order means a shorter bond, so CO < CO₂ < CO₃²⁻.
Q58AIPMT 2006 Prelims · Q89
In which of the following molecules are all the bonds not equal ?
Not quite — the answer is A.
ClF₃ has 3 bond pairs and 2 lone pairs on Cl (sp³d), giving a T shape with two longer axial Cl–F bonds and one shorter equatorial bond. BF₃ and AlF₃ are trigonal planar and NF₃ is pyramidal, each with three identical bonds.
Q59AIPMT 2006 Prelims · Q90
The electronegativity difference between N and F is greater than that between N and H yet the dipole moment of NH₃ (1.5 D) is larger than that of NF₃ (0.2 D). This is because :
Not quite — the answer is B.
In NH₃ the lone pair's orbital dipole points away from N, the same way as the N–H bond dipoles (towards N), so they add up to 1.5 D. In NF₃ the N–F bond dipoles point towards the F atoms, opposite to the lone-pair dipole, so they largely cancel, leaving only 0.2 D.
Q60AIPMT 2006 Prelims · Q93
Which of the following species has a linear shape ?
Not quite — the answer is C.
NO₂⁺ has two bond pairs and no lone pair on N (sp hybridised), like the isoelectronic CO₂, so it is linear. NO₂⁻, SO₂ and O₃ each have a lone pair on the central atom and are bent.
Q61AIPMT 2006 Prelims · Q96
Which of the following is not a correct statement ?
Not quite — the answer is C.
AB₅ molecules with no lone pair, such as PCl₅, are trigonal bipyramidal; only those with a lone pair (AB₅E, e.g. BrF₅) are square pyramidal. So the claim that every AB₅ molecule is square pyramidal is false. The other three statements are standard facts.
Q62AIPMT 2006 Prelims · Q97
The number of unpaired electrons in a paramagnetic diatomic molecule of an element with atomic number 16 is :
Not quite — the answer is A.
Z = 16 is sulphur. S₂ is isoelectronic in its valence shell with O₂, and its two highest electrons occupy the two degenerate π* orbitals singly (Hund's rule). So S₂ has 2 unpaired electrons and is paramagnetic.
Q63AIPMT 2006 Prelims · Q99
Which of the following is not isostructural with SiCl₄ ?
Not quite — the answer is A.
SiCl₄, SO₄²⁻, PO₄³⁻ and NH₄⁺ all have four bond pairs and no lone pair on the central atom, so they are tetrahedral. SCl₄ has four bond pairs and one lone pair on S (sp³d), giving a see-saw shape, so it is not isostructural.
Q64AIPMT 2005 Prelims · Q56
The correct order in which the O — O bond length increases in the following is :
Not quite — the answer is C.
O–O bond order: O₂ = 2, O₃ = 1.5 (resonance), H₂O₂ = 1. Bond length increases as bond order decreases, so O₂ < O₃ < H₂O₂.
Q65AIPMT 2005 Prelims · Q62
Which of the following molecules has trigonal planar geometry ?
Not quite — the answer is D.
BF₃ has three bond pairs and no lone pair on boron (sp²), so it is trigonal planar. PCl₃ and NH₃ are pyramidal (one lone pair) and IF₃ is T-shaped (two lone pairs).
Q66AIPMT 2005 Prelims · Q68
The correct sequence of increasing covalent character is represented by :
Not quite — the answer is C.
By Fajans' rules, a smaller, more highly charged cation polarises Cl⁻ more. Polarising power Na⁺ < Li⁺ < Be²⁺, so covalent character NaCl < LiCl < BeCl₂.
Q67AIPMT 2005 Prelims · Q81
Which of the following would have a permanent dipole moment ?
Not quite — the answer is C.
SF₄ has 4 bond pairs and 1 lone pair (see-saw), so its bond dipoles do not cancel. BF₃ (trigonal planar), SiF₄ (tetrahedral) and XeF₄ (square planar) are symmetric with zero net dipole.
Q68AIPMT 2005 Prelims · Q90
Which one of the following oxides is expected to exhibit paramagnetic behaviour ?
Not quite — the answer is C.
ClO₂ has an odd number of electrons (33), so it has an unpaired electron and is paramagnetic. CO₂, SO₂ and SiO₂ have all electrons paired.
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