JEE Main Previous Year Papers Questions With Solutions Chemistry Chemical Bonding and Molecular Structure

JEE Main Previous Year Papers Questions With Solutions Chemistry Chemical Bonding and Molecular Structure

Ans.(1) In NH₃ and BF₄^– the hybridisation is sp³ and the bond angle is almost 109°28 ’

2.In XeF₂, XeF₄, XeF₆ the number of lone pairs of Xe are respectively (2002)
(1)2, 3, 1     2) 1, 2, 3          3) 4, 1, 2         4) 3, 2, 1
Ans.(4) XeF₂          sp³d               4 lone pairs
XeF₄          sp³d²              2 lone pairs
XeF₆          sp³d³              1 lone pair

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4.Which of the following statements is true?
(1)HF is less polar than HBr (2002)
(2)absolutely pure water does not contain any ions
(3)chemical bond formation take place when forces of attraction overcome the forces of repulsion
(4)in covalency transference of electron takes place
Ans.(3) Bond formation is exothermic.

5.In which of the following species is the underlined carbon having sp³ hybridisation ?(2002)
1) CH₃COOH                         2) ch₃ch₂oh
3) GH₃COCH₃             4) CH₂ = CH – CH₃
Ans.(2) In molecules (a), (c) and (d), the carbon atom has a multiple bond, only in molecule (b) carbon has sp³ hybridisation.

6.In the anion HCOO” the two carbon -oxygen bonds are found to be of equal length. What is the reason for it ?       (2003)
(1)The C=0 bond is weaker than the C-O bond
(2)The anion HCOO” has two resonating structures
(3)The anion is obtained by removal of a proton from the acid molecule
(4)Electronic orbitals of carbon atom are hybridised
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Ans.(2) In H₂S, due to low electronegativity of sulphur the L.P.-L.P repulsion is more than B.P.- B.P. repulsion and hence the bond angle in H₂S is 92°.

8.The pair of species having identical shapes for molecules of both species is                  (2003)
1) XeF₂, CO                           2) BF₃, PC1₃
3) PF₅, IF₅                4) CF₄, SF₄
Ans.(1) Both XeF₂ and C0₂ have a linear structure.

9.Which one of the following pairs of molecules will have permanent dipolemoments for both members ?     (2003)
1) N0₂ and C0₂  2) N0₂ and 0₃
3) SiF₄ and C0₂  4) SiF₄ and N0₂
Ans.(2) Both N0₂ and 0₃ have angular shape and hence will have net dipole moment.

10.The correct order of bond angles (smallest first) in H₂S, NH₃, BF₃ and SiH₄ is (2004)
(1)H₂S < SiH₄ < NH₃ < BF₃
(2)H₂S < NH₃ < BF₃ < SiH₄
(3)H₂S < NH₃ < SiH₄ < BF₃
(4)NH₃ < H₂S < SiH₄ < BF₃
Ans.(3)H₂S—— > sp³ NH₃——– > sp³
BF₃—- > sp²                  SiH₄——– > sp³

11.The bond order in NO is 2.5 while that in NO⁺is 3. Which of the following statements is true for these two species?  (2004)
(1)Bond length in NO⁺ is greater than in NO
(2)Bond length is unpredictable
(3)Bond length in NO⁺ in equal to that in NO
(4)Bond length in NO is greater than in NO⁺
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12.The states of hybridization of boron and oxygen atoms in boric acid (H₃B0₃) are respectively    (2004)
1) sp² and sp²                         2) sp³ and sp³
3) sp³ and sp²                         4) sp² and sp³
Ans.(4) B is sp² and O is sp³

13.The maximum number of 90° angles between bond pair of electrons is observed in (2004)
1) dsp³ hybridization 2) sp³d² hybridization 3) dsp² hybridization 4) sp³d hybridization
Ans.(2) sp³d² hybridisation confirms to octahedral or square bipyramidal configuration.All the bond angles are 90° in the structure

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15.Lattice energy of an ionic compounds depends upon  (2005)
1) Chaige on the ion only
2) Size of the ion only
(3)Packing of ions only
(4)Charge on the ion and size of the ion
Ans.(4) Lattice energy will be more if, charge is high and size is low.

16.The molecular shapes of SF₄, CF₄ and XeF₄ are (2005)
(1)the same with 2, 0 and 1 lone pairs of electrons on the central atom, respectively
(2)the same with 1,1 and 1 lone pair of electrons on the central atoms, respectively
(3)different with 0, 1 and 2 lone pair of electrons on the central atoms, respectively
(4)different with 1, 0 and 2 lone pairs of electron on the central atoms respectively
Ans.(4) Number of lone pairs on S is 1 and on Xe is 2

17.The number and type of bonds between two carbon atoms in calcium carbide are (2005)
1) One sigma, one pi           2) One sigma, two  pi
3) Two sigma, one pi           4) Two sigma, two  pi
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18.

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20.Among the following mixtures, dipole-dipole as the major interaction, is present in (2006)
(1)benzene and ethanol
(2)acetonitrile and acetone
(3)KC1 and water
(4)benzene and carbon tetrachloride
Ans.(2) CH₂ = CHCN and CH₃COCH₃ are polar molecules.

21.In which of the following molecules/ions are all the bonds not equal ?         (2006)
1) SF₄             2) SiF₄             3) XeF₄            4) BF₄
Ans.(1) S in SF₄ has one Lone pair

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24.Which of the following hydrogen bonds is the strongest ?    (2007)
1) O-H………… N                    2) F-H…………. F
3) O-H………… O                     4) O-H………… F
Ans.(2) The hydrogen bond in HF is strongest, because fluorine is the most electronegative element.

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Ans.(1) Both are isoelectronic and have same bond order.

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28. The bond dissociation energy of B – F in BF₃  is 646 kj mol’¹ where as that of C – F in CF₄ is 515 kj mol^-1. The correct reason for higher B-F bond dissociation energy as compared to that of C – F is      (2009)
(1)smaller size of B-atom as compared to that of C -atom
(2)stronger o bond between B and F is BF₃ as compared to that between C and F in CF₄
(3)significant pn-pn interaction between B and F in BF₃ where as there is no possibility of such interaction between C and F in CF..
(4)lower degree of pn-pn interaction between B and F in BF₃ than that between C and F in cf₄.
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30.Among the following the maximum covalent character is shown by the compound (2011)
(1)A/C/₃ 2) MgC/₂ 3) FeC/₂ 4) SnC/₂
Ans.(1) According to Fajan’s rule, polarisation is proportional to charge on cation in turn polarisation is proportional to covalent character A/⁺³ C/₃, Mg⁺²C/₂, Fe⁺²C/₂ and Sn⁺² C/₂ A/CZ₃ is most covalent

31.The structure of IF₇ is (2011)
(1) octahedral
(2)pentagonal bipyramid
(3)square pyramid    (4) trigonal bipyramid
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33.The molecule having smallest bond angle is
1) nci_{3               2)AsCl}
3) SbCl₃         4) PC1₃
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34.Ortho-Nitrophenol is less soluble in water than p-and m-Nitrophenols because (2012)
(1)o-Nitrophenol is more voltaile is steam than those of m- and p- isomers
(2)o-Nitrophenol shows Intramolecular H-bonding
(3)o-Nitrophenol shows Intermolecular H-bonding
(4)Melting point of o-Nitrophenol lower than those of m- and p-isomers
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36.Which one of the following molecules is expected to exhibit diamagnetic behaviour ?(2013)
1) C₂ 2) N₂ 3) 0₂       4) S₂
Ans.(1, 2) According to MO theory in N₂ and C₂ all electrons are paired. So diamagnetic.

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41.The inter molecular interaction that is dependent on the inverse cube of distance between the molecular is   (2015)
(1)ion-ion interaction
(2)ion-dipole interaction
(3)London force 4) hydrogen bond

Ans.(4) Hydrogen bond is the type of dipole-dipole interaction.