02 Chemical Bonding Quiz - Chemistry QuizIn this Chemistry quiz section, we are going to serve Chemistry study materials and some multiple-choice questions from following topics like Electrovalent bonding; Covalent bonding; Co-ordinate or Dative bonding; Dipole moment; Polarisation and Fajan's rule; Overlapping- sigma and pi- bonds; Hybridisation; VSEPR Theory; Molecular orbital theory and Hydrogen bonding.
Chemical BondingCovalent bond
Covalent bond was first proposed by Lewis in 1916. The bond formed between the two atoms by mutual sharing of electrons so as to complete their octets or duplets (in case of elements having only one shell) is called covalent bond or covalent linkage. A covalent bond between two similar atoms is a non-polar covalent bond while it is polar between two different atom having different electronegativities. A covalent bond may be single, double or a triple bond. We explain covalent bond formation by Lewis octet rule.
Covalent bond was first proposed by Lewis in 1916. The bond formed between the two atoms by mutual sharing of electrons so as to complete their octets or duplets (in case of elements having only one shell) is called covalent bond or covalent linkage. A covalent bond between two similar atoms is a non-polar covalent bond while it is polar between two different atom having different electronegativities. The covalent bond may be single, double or a triple bond. We explain covalent bond formation by Lewis octet rule.
(1) Conditions for formation of covalent bond
(i) The combining atoms should be short by 1, 2 or 3 electrons in the valency shell in comparison to stable noble gas configuration.
(ii) Electronegativity difference between the two atoms should be zero or very small.
(iii) The approach of the atoms towards one another should be accompanied by decrease of energy.
(2) Characteristics of covalent compounds(i) These exist as gases or liquids under the normal conditions of temperature and pressure. Some covalent compounds exist as soft solids.
(ii) Diamond, Carborandum (SiC), Silica (SiO2), AlN, etc. have giant three-dimensional network structures; therefore have exceptionally high melting points otherwise these compounds have relatively low melting and boiling points.
(iii) In general covalent substances is a bad conductor of electricity. Polar covalent compounds like HCl in solution conduct electricity. Graphite can conduct electricity in solid state since electrons can pass from one layer to the other.
(iv) These compounds are generally insoluble in polar solvent like water but soluble in non-polar solvents like benzene etc. some covalent compounds like alcohol, dissolve in water due to hydrogen bonding.
(v) The covalent bond is rigid and directional. These compounds, thus show isomerism (structural and space).
(vi) Covalent substances show molecular reactions. The reaction rates are usually low.
(vii) The number of electrons contributed by an atom of the element for sharing with other atoms is called the covalency of the element. Covalency = 8 – [Number of the group to which element belongs]. The variable covalency of an element is equal to the total number of unpaired electrons in s, p, and d-orbitals of its valency shell.
1. Which type of compounds show high melting and boiling points
(a) Electrovalent compounds
(b) Covalent compounds
(c) Coordinate compounds
(d) All three types of compounds have equal melting and boiling points
SOL: (a) Melting point and boiling point of electrovalent compounds are high due to strong electrostatic force of attraction between the ions.
2. Lattice energy of an ionic compound depends upon
(a) Charge on the ion only
(b) Size of the ion only
(c) Packing of ions only
(d) Charge on the ion and size of the ion
SOL: (d) The value of lattice energy depends on the charges present on the two ions and distance between them. It shell be high if charges are high and ionic radii are small.
3. In the formation of NaCl from Na and Cl
(a) Sodium and chlorine both give electrons
(b) Sodium and chlorine both accept electrons
(c) Sodium loses electron and chlorine accepts an electron
(d) Sodium accepts electron and chlorine loses an electron
4. Electrovalent compounds do not have
(a) High M.P. and Low B.P.
(b) High dielectric constant
(c) High M.P. and High B.P.
(d) High polarity
SOL: (a) Electrovalent compounds generally have high m.pt and high b.pt due to stronger coulombic forces of attractions.
5. Many ionic crystals dissolve in water because
(a) Water is an amphiprotic solvent
(b) Water is a high boiling liquid
(c) The process is accompanied by a positive heat of solution
(d) Water decreases the interionic attraction in the crystal
lattice due to salvation
SOL: (d) Water is a polar solvent so it decreases the interionic attraction in the crystal lattice due to solvation.
6. In the transition of Zn atoms to Zn++ ions there is a decrease in the
(a) Number of valency electrons
(b) Atomic weight
(c) Atomic number
(d) Equivalent weight
SOL: (a) Ion is formed by gaining or losing electrons. To form cation electron are lost from the valency shell, so Zn atoms to Zn++ ions there is a decrease in the no. of valence electron.
7. Sodium chloride easily dissolves in water. This is because
(a) It is a covalent compound
(b) Salt reacts with water
(c) It is a white substance
(d) Its ions are easily solvated
SOL: (d) Sodium chloride is an electrovalent compound so it dissolves in water which is a polar solvent.
8. When NaCl is dissolved in water the sodium ion becomes
(a) Oxidized (b) Reduced
(c) Hydrolysed (d) Hydrated
SOL: (d) When sodium chloride is dissolved in water, the sodium ion is hydrated.
9. Solid NaCl is a bad conductor of electricity since
(a) In solid NaCl there are no ions
(b) Solid NaCl is covalent
(c) In solid NaCl there is no motion of ions
(d) In solid NaCl there are no electrons
10. Favourable conditions for electrovalency are
(a) Low charge on ions, large cation, small anion
(b) High charge on ions, small cation, large anion
(c) High charge on ions, large cation, small anion
(d) Low charge on ions, small cation, large anion
11. Ionic bonds are usually formed by combination of elements with
(a) High ionisation potential and low electron affinity
(b) Low ionisation potential and high electron affinity
(c) High ionisation potential and high electron affinity
(d) Low ionisation potential and low electron affinity
12. Molten sodium chloride conducts electricity due to the presence of
(a) Free electrons
(b) Free ions
(c) Free molecules
(d) Atoms of sodium and chlorine
SOL: (b) Molten sodium chloride conducts electricity due to the presence of free ions.
13. Out of the following, which compound will have electrovalent bonding
(c) Calcium chloride
SOL: (c) CaCl2 will have electrovalent bonding because calcium is electropositive metal while chlorine is electronegative so they will combined with electrovalent bond.
14. The force which holds atoms together in an electrovalent bond is
(a) Vander Waal's force
(b) Dipole attraction force
(c) Electrostatic force of attraction
(d) All the above
15. The main reaction during electrovalent bond formation is
(a) Redox reaction
(b) Substitution reaction
(c) Addition reaction
(d) Elimination reaction
SOL: (a) Electrovalent bond is formed by losing electrons from one atom and gaining electron by other atom i.e. redox reaction.
16. Electrovalent compounds are
(a) Good conductor of electricity
(b) Polar in nature
(c) Low M.P. and low B.P.
(d) Easily available
SOL: (b) Electrovalent compound are polar in nature because they are formed by ions.
17. Ionic compounds do not have
(a) Hard and brittle nature
(b) High melting and boiling point
(c) Directional properties
(d) Soluble in polar solvents
18. What is the effect of more electronegative atom on the strength of ionic bond
(a) Decreases (b) Increases
(c) Decreases slowly (d) Remains the same
SOL:(b) As soon as the electronegativity increases, ionic bond strength increases.
19. Which type of bonding exists in Li2O and CaF2 respectively
(a) Ionic, ionic
(b) Ionic, covalent
(c) Covalent, ionic
(d) Coordinate, ionic
SOL: (a) Lithium oxide and calcium fluoride show ionic characters.
20. An atom with atomic number 20 is most likely to combine chemically with the atom whose atomic number is
(a) 11 (b) 14
(c) 16 (d) 10
21. The nature of bonding in graphite is
(a) Covalent (b) Ionic
(c) Metallic (d) Coordinate
SOL: (a)In graphite all carbon atoms are sp2 -hybridised and have covalent bond.
22. Which of the following substances has giant covalent structure
(a) Iodine crystal
(b) Solid CO2
(d) White phosphorus
SOL: (c) Silica has tendency to form long chain covalent structure such as carbon so it has giant covalent structure.
23. With which of the given pairs CO2 resembles
(a) HgCl2, C2H2
(b) HgCl2, SnCl4
(c) C2H2, NO2
(d) N2O and NO2
SOL: (d)Similar atoms form covalent bond.
24. The electron pair which forms a bond between two similar non-metallic atoms will be
(a) Dissimilar shared between the two
(b) By complete transfer from one atom to other
(c) In a similar spin condition
(d) Equally shared in between the two
SOL: (d) Similar atoms form covalent bond.
25. For the formation of covalent bond, the difference in the value of electronegativities should be
(a) Equal to or less than 1.7
(b) More than 1.7
(c) 1.7 or more
(d) None of these
SOL: (a) Covalent bond forms when electronegativity difference of two atom is equal to 1.7 or less than 1.7
26. Which type of bond is formed between similar atoms
(a) Ionic (b) Covalent
(c) Coordinate (d) Metallic
SOL: (b) Similar atoms form covalent bond.
27. Covalent compounds are generally ...... in water
(a) Soluble (b) Insoluble
(c) Dissociated (d) Hydrolysed
SOL: (b)Water is a polar solvent while covalent compounds are non-polar so they usually insoluble in water.
28. Silicon has 4 electrons in the outermost orbit. In forming the bonds
(a) It gains electrons
(b) It loses electrons
(c) It shares electrons
(d) None of these
29. Bond energy of covalent O-H bond in water is
(a) Greater than bond energy of H- bond
(b) Equal to bond energy of H- bond
(c) Less than bond energy of H- bond
(d) None of these
30. Solid CH4 is
(a) Molecular solid
(b) Ionic solid
(c) Pseudo solid
(d) Does not exist
31. A covalent bond is likely to be formed between two elements which
(a) Have similar electronegativities
(b) Have low ionization energies
(c) Have low melting points
(d) Form ions with a small charge
32. 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
33. Which of the following substances has covalent bonding
(b) Sodium chloride
(c) Solid neon
34. The covalency of nitrogen in HNO3 is
(a) 0 (b) 3
(c) 4 (d) 5
35. Hydrogen chloride molecule contains a
(a) Covalent bond
(b) Double bond
(c) Coordinate bond
(d) Electrovalent bond
SOL: (a)HCl molecule has covalent bond.
36. As compared to covalent compounds, electrovalent compounds generally have
(a) Low melting points and low boiling points
(b) Low melting points and high boiling points
(c) High melting points and low boiling points
(d) High melting points and high boiling points
SOL: (d)Electrovalent compounds have high melting point and high boiling point.
37. The number of electrons shared by each outermost shell of N2 is
(a) 2 (b) 3
(c) 4 (d) 5
SOL: (b)Each nitrogen share 3 electrons to form triple bond.
38. Which of the following substances when dissolved in water will give a solution that does not conduct electricity
(a) Hydrogen chloride
(b) Potassium hydroxide
(c) Sodium acetate
SOL: (d)Urea solution does not conduct electricity because it is a covalent compound
39. Which of the following atoms has minimum covalent radius
(a) B (b) C
(c) N (d) Si
40. Boron form covalent compound due to
(a) Small size (b) Higher ionization energy
(c) Lower ionization energy
(d) Both (a) and (b)
SOL: (d) Due to the small size and higher ionization energy, boron forms covalent compound.
41. Covalent compounds have low melting point because
(a) Covalent bond is less exothermic
(b) Covalent molecules have definite shape
(c) Covalent bond is weaker than ionic bond
(d) Covalent molecules are held by weak Vander Waal’s force of attraction
42. p and n-type of semiconductors are formed due to
(a) Covalent bonds
(b) Metallic bonds
(c) Ionic bonds
(d) Co-ordinate bond
43. Valency of sulphur in Na2S2O3 is
(a) Two (b) Three
(c) Four (d) Six
44. A coordinate bond is formed when an atom in a molecule has
(a) Electric charge on it
(b) All its valency electrons shared
(c) A single unshared electron
(d) One or more unshared electron pair
45. The number of dative bonds in sulphuric acid molecules is
(a) 0 (b) 1
(c) 2 (d) 4
46. Sulphuric acid provides a example of
(a) Co-ordinate bonds
(b) Non-covalent compound
(c) Covalent and co-ordinate bond
(d) Non-covalent ion
SOL: (c) Sulphuric acid contain, covalent and co-ordinate bond.
47. Which molecule has the largest dipole moment
(a) HCl (b) HI
(c) HBr (d) HF
SOL: (d) HF has largest dipole moment because electronegativity difference of both is high so it is highly polar.
48. The unequal sharing of bonded pair of electrons between two atoms in a molecule causes
(b) Radical formation
(c) Covalent bond
(d) Decomposition of molecule
49. Which of the following will show least dipole character
(a) Water (b) Ethanol
(c) Ethane (d) Ether
SOL: (c)Due to its symmetrical structure.
50. Which of the following molecules will show dipole moment
(a) Methane (b) Carbon tetrachloride
(c) Chloroform (d) Carbon dioxide
SOL: (c) Chloroform has 3 chlorine atom and one hydrogen atom attached to the carbon so it is polarised and it will show dipole moment.
51. Which of the following compounds possesses the dipole moment
(a) Water (b) Boron trifluoride
(c) Benzene (d) Carbon tetrachloride
52. Carbon tetrachloride has no net dipole moment because of
(a) Its planar structure
(b) Its regular tetrahedral structure
(c) Similar sizes of carbon and chlorine atoms
(d) Similar electron affinities of carbon and chlorine
SOL: (b) CCl4 has no net dipole moment because of its regular tetrahedral structure.
53. The polarity of a covalent bond between two atoms depends upon
(a) Atomic size
(c) Ionic size
(d) None of the above
54. Which one has minimum (nearly zero) dipole moment
(b) cis butene-2
(c) trans butene-2
55. Non-polar solvent is
(a) Dimethyl sulphoxide
(b) Carbon tetrachloride
(d) Ethyl alcohol
Polarisation and Fajan's rule
56. If the electron pair forming a bond between two atoms A and B is not in the centre, then the bond is
(a) Single bond (b) Polar bond
(c) Non-polar bond (d) pi bond
SOL: (b) When electronegativity difference is more between two joined atoms then covalent bond becomes polar and electron pair forming a bond don’t remain in the centre.
57. Which of the following liquids is not deflected by a non-uniform electrostatic field
(a) Water (b) Chloroform
(c) Nitrobenzene (d) Hexane
SOL: (d) Hexane has symmetrical structure so does not have polarity.
58. Polarization is the distortion of the shape of an anion by an adjacently placed cation. Which of the following statements is correct
(a) Maximum polarization is brought about by a cation of high charge
(b) Minimum polarization is brought about by a cation of
(c) A large cation is likely to bring about a large degree of polarization
(d) A small anion is likely to undergo a large degree of polarization
SOL: (a) According to Fajan’s rule, polarisation of anion is influenced by charge and size of cation more is the charge on cation, more is polarisation of anion.
59. The bonds between P atoms and Cl atoms in PCl5 are likely to be
(a) Ionic with no covalent character
(b) Covalent with some ionic character
(c) Covalent with no ionic character
(d) Ionic with some metallic character
60. Two electrons of one atom A and two electrons of another atom B are utilized to form a compound AB. This is an example of
(a) Polar covalent bond
(b) Non-polar covalent bond
(c) Polar bond
(d) Dative bond
SOL: (a) When two atoms shares two electrons it is an example of covalent bond. This covalent bond may be polar or may be non-polar depends on the electronegativity difference. In given example formula is AB. So it is polar.
61. Which of the following possesses highest melting point
SOL: (d) p-dichloro benzene have highest melting point.
Overlaping- sigma and pi- bonds
62. The number of sigma and pi bonds in 1-butene-3-yne are
(a) 5 sigma and 5 pi
(b) 7 sigma and 3 pi
(c) 8 sigma and 2 pi
(d) 6 sigma and 4 pi
63. Which of the following is not correct
(a) A sigma bond is weaker than pi bond
(b) A sigma bond is stronger than pi bond
(c) A double bond is stronger than a single bond
(d) A double bond is shorter than a single bond
64. Strongest bond formed, when atomic orbitals
(a) Maximum overlap
(b) Minimum overlap
(c) Overlapping not done
(d) None of them
65. The p-p orbital overlapping is present in the following molecule
(b) Hydrogen bromide
(c) Hydrogen chloride
66. In N2 molecule, the atoms are bonded by
(a) One , Two
(b) One , One
(c) Two , One
(d) Three bonds
67. Number of bonds in SO2
(a) Two and two
(b) Two and one
(c) Two , two and one lone pair
(d) None of these
68. Number of sigma bonds in P4O10 is
(a) 6 (b) 7
(c) 17 (d) 16
69. Percentage of s-character in sp3 hybrid orbital is
(a) 25 (b) 50
(c) 66 (d) 75
70. Shape of XeF4 molecule is
(a) Linear (b) Pyramidal
(c) Tetrahedral (d) Square planar
71. Shape of methane molecule is
(d) Square planer
SOL: (a)In methane molecule C is sp3 hybridised so its shape will be tetrahedral.
72. When two pairs of electrons are shared, bond is
(a) Single covalent bond (b) Double covalent bond
(c) Dative bond (d) Triple bond
73. Number of shared electrons in between carbon-carbon atoms in ethylene molecule is
(a) 2 (b) 4
(c) 6 (d) 3
74. The two types of bonds present in B2H6 are covalent and
(a) Three centre bond
(b) Hydrogen bond
(c) Two centre bond
(d) None of the above
75. The structure of PF5 molecule is
(b) Trigonal bipyramidal
(c) Square planar
(d) Pentagonal bipyramidal
SOL: (b)PF5 involves sp3d hybridization and hence has trigonal bipyramidal structure.
76. Hybridisation involves
(a) Addition of an electron pair
(b) Mixing up of atomic orbitals
(c) Removal of an electron pair
(d) Separation of orbitals
SOL: (b) Merging (mixing) of dissimilar orbitals of different energies to form new orbitals is known as hybridisation and the new orbital formed are known as hybrid oribitals. They have similar energy.
77. The geometry of sulphur trioxide molecule is
(b) Trigonal planar
(d) Square planar
SOL: (b) In SO3 sulphur is sp2 hybridized so its shape will be trigonal planar.
78. XeF6 is
(b) Distorted octahedral
79. In which of the following is the angle between the two covalent bonds greatest
(a) CO2 (b) CH4
(c) NH3 (d) H2O
SOL: (a) CO2 has bond angle 180
80. As the s-character of hybridized orbital decreases, the bond angle
(c) Does not change
(d) Becomes zero
SOL: (a)As the s-character of hybridized orbitals decreases the bond angle also decreases
81. XeF2 molecule is
(b) Triangular planar
(d) Square planar
SOL: (a) XeF2 molecule is Linear because Xe is sp hybridised.
82. In BrF3 molecule,the lone pairs occupy equatorial positions to minimize
(a) Lone pair- lone pair repuilsion and lone pair-bond pair repulsion
(b) Lone pair- lone pair repulsion only
(c) Lone pair- bond pair repulsion only
(d) Bond pair- bond pair repulsion only
Molecular orbital theory
83. Molecular orbital theory was developed mainly by
(b) Pauling and Slater
84. The bond order of a molecule is given by
(a) The difference between the number of electrons in bonding and antibonding orbitals
(b) Total number of electrons in bonding and antibonding orbitals
(c) Twice the difference between the number of electrons in bonding and antibonding electrons
(d) Half the difference between the number of electrons in bonding and antibonding electrons
85. Oxygen molecule is paramagnetic because
(a) Bonding electrons are more than antibonding electrons
(b) Contains unpaired electrons
(c) Bonding electrons are less than antibonding electrons
(d) Bonding electrons are equal to antibonding electrons
86. Which of the following molecule is paramagnetic
(a) Chlorine (b) Nitrogen
(c) Oxygen (d) Hydrogen
SOL: (c) Oxygen is paramagnetic due to the presence of two unpaired electron
87. The bond order in N2 molecule is
(a) 1 (b) 2
(c) 3 (d) 4
88. When two atoms of chlorine combine to form one molecule of chlorine gas, the energy of the molecule (a) Greater than that of separate atoms
(b) Equal to that of separate atoms
(c) Lower than that of separate atoms
(d) None of the above statement is correct
SOL: (c)When bond forms between two atom then their energy get lower than that of separate atoms because bond formation is an exothermic process.
89. The bond order of individual carbon-carbon bonds in benzene is
(c) Between 1 and 2
(d) One and two alternately
SOL: (c) Due to resonance bond order of C-C bonds in benzene is between 1 and 2.
90. Paramagnetism is exhibited by molecules
(a) Not attracted into a magnetic field
(b) Containing only paired electrons
(c) Carrying a positive charge
(d) Containing unpaired electrons
SOL: (d)Molecules having unpaired electrons show paramagnetism.
91. Contrary to other hydrogen halides, hydrogen fluoride is a liquid because
(a) Size of F atom is small
(b) HF is a weak acid
(c) HF molecule are hydrogen bonded
(d) Fluorine is highly reactive
92. As a result of hybridization, we get
(a) Two mutual perpendicular orbitals
(b) Two orbitals at 180
(c) Four orbitals in tetrahedral directions
(d) Three orbitals in the same plane
SOL: (b) sp-hybridization gives two orbitals at 180 with Linear structure.
93. The reason for exceptionally high boiling point of water is
(a) Its high specific heat
(b) Its high dielectric constant
(c) Low ionization of water molecules
(d) Hydrogen bonding in the molecules of water
SOL: (d) Hydrogen bonding increases the boiling point of compound.
94. Which concept best explains that o-nitrophenol is more volatile than p-nitrophenol
(c) Hydrogen bonding
(d) Steric hindrence
SOL: (c) o-Nitrophenol has intramolecular hydrogen bonding but p-Nitrophenol has intermolecular hydrogen bonding so boiling point of p-Nitrophenol is more than o-Nitrophenol.
95. The hydrogen bond is strongest in
(a) Water (b) Ammonia
(c) Hydrogen fluoride (d) Acetic acid
SOL: (c)Hydrogen bond is strongest in hydrogen fluoride.
96. Methanol and ethanol are miscible in water due to
(a) Covalent character
(b) Hydrogen bonding character
(c) Oxygen bonding character
(d) None of these
97. Strength of hydrogen bond is intermediate between
(a) Vander Waal and covalent
(b) Ionic and covalent
(c) Ionic and metallic
(d) Metallic and covalent
98. In which of the following compounds intramolecular hydrogen bond is present
(a) Ethyl alcohol
(d) Hydrogen sulphide
99. Hydrogen bonding is formed in compounds containing hydrogen and
(a) Highly electronegative atoms
(b) Highly electropositive atoms
(c) Metal atoms with d-orbitals occupied
SOL: (a) Hydrogen bond is formed when hydrogen is attached with the atom which is highly electronegative and having small radius.
100. The high density of water compared to ice is due to
(a) Hydrogen bonding interactions
(b) Dipole-dipole interactions
(c) Dipole-induced dipole interactions
(d) Induced dipole-induced dipole interactions
SOL: (a)Water is dense than ice because of hydrogen bonding interaction and structure of ice.
101. Which one has the highest boiling point
(b) Ethyl alcohol
(c) Diethyl ether
SOL: (b)Ethyl alcohol has a intermolecular hydrogen bond.
102. Hydrogen bond energy is equal to
(a) 3 – 7 cals
(b) 30 – 70 cals
(c) 3 – 10 kcals
(d) 30 – 70 kcals
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