Class 11 Chemistry Chemical Bonding Important MCQs with Brief Answers for Exams:
A theory that explains the formation of a covalent bond by the sharing of electrons is :
1.VSEPR
2.VBT
3.MOT
4.KMT
Answer ) VBT (Valence bond theory)
Brief Explanation :
Valence bond theory explains the formation of a covalent bond in terms of the overlapping of half-filled atomic orbitals.
It also explains the strength of a covalent bond in terms of nature and the extent of overlapping of orbitals.
Sigma bond is formed by the Head-on overlapping of atomic orbitals:
1.s-s
2.p-p
3.s-p
4.All of these
Answer ) All of these
Brief Explanation :
The s-s, p-p, and s-p half-filled atomic orbitals combine from front to front along the same axis to form a sigma bond.
Pi bond is formed by the sidewise overlap of two p-p orbitals which are :
1.Half-filled
2.Parallel
3.On covalently bonded adjacent atoms
4.All of these
Answer ) All of these
Brief Explanation :
Two parallel half-filled p-p orbitals on adjacent and covalently bonded atoms combine with each other from the sides to form a pi bond.
All single bonds are always :
1.Sigma
2.Pi
3.Co-ordinate
4.Metallic
Answer ) Sigma
Brief Explanation :
All singe bonds are always sigma bonds. A pi bond is always formed in addition to the sigma bond.
For example, a double or triple bond contains only one sigma bond. A double bond contains one pi bond whereas the triple bond contains 2 pi bonds.
Orbitals usually lying angle of 1200 from each other are:
1.sp3 orbitals
2.sp2 orbitals
3.sp orbitals
4.All of these
Answer ) sp2 orbitals
Brief Explanation :
The sp2 orbitals lie in one plane at an angle of 1200 from each other , resulting in a Trigonal planar geometry.
A molecule/ion in which the central atom is sp hybridized is:
1.Linear
2.Tetrahedral
3.Trigonal planar
4.Square plan
Answer )linear
Brief Explanation :
A molecule/ion in which the central atom is sp hybridized has a linear structure. The sp-orbitals are co-planar and lie at an angle of 1800 from each other, resulting in a linear geometry.
When sum ( of atoms attached + lone pairs ) around central atom in a molecule or ion is three , then it is hybridized :
1.sp3
2.sp2
3.sp
4.dsp2
Answer ) sp2
Brief Explanation :
The type of hybridization of the central atom in a molecule/ion can be determined from the total number of atoms attached to & lone pair of electrons in its valence shell.
When the total number (atoms attached + lone pairs ) for the central atom is:
Two, then the central atom is sp-hybridized.
Three, then the central atom is sp2-hybridized.
Four, then the central atom is sp3-hybridized.
Hybridization of carbon in CH3-O-CH3 is :
1.sp3
2.sp2
3.sp
4.dsp2
Answer ) sp3
Brief Explanation :
Carbon in CH3-O-CH3 (Dimethyl ether ) is sp3 hybridized and has a bent shape.
Carboxylic acid in acetic acid [ CH3-CO-OH ] is hybridized:
1.Sp
2.sp2
3.sp3
4.dsp2
Answer ) sp2
Brief Explanation :
Carboxylic acid in acetic acid [ CH3-CO-OH ] is attached to three other atoms and thus sp2 hybridized.
A molecule with the smallest angle b/w two adjacent bonds, is:
1.CO2
2.CH4
3.NH3
4.H2O
Answer ) H2O
Brief Explanation :
H2O molecule with the smallest angle b/w two adjacent bonds due to the compression of two bond pairs by the two lone pairs of electrons on the oxygen atom,
A molecular orbital with higher energy than the atomic orbitals ,is:
1.BMO
2.ABMO
3.Hybrid orbitals
4.Un-Hybrid orbitals
Answer ) ABMO
Brief Explanation :
An anti bonding MO has always higher energy than the atomic orbitals .
When s-character of a hybrid orbital increases , bond length :
1.Remains constant
2.Increases
3.Decreases
4.Not well defined
Answer ) Decreases
Brief Explanation :
When s-character of a hybrid orbital increases , bond length decreases .
For example , C-C bond length in ethane (sp3) , ethylene (sp2)
And acetylene ( sp) are 1.54 Ao , 1.34 Ao & 1.20 Ao .
Dipole moment is generally expressed in units of Debye (D):
1.1 D = 1.6 X 10 23 C.m
2.1 D = 3.34 X 10 -19 C.m
3.1 D = 3.34 X 10 -30 C.m
4.1 D = 6.62 X 10 -34 C.m
Answer ) 1 D = 3.34 X 10
Brief Explanation :
Dipole moment is generally expressed in units of Debye (D) in C.G.S system .Its S.I unit is coulombs x meter (c.m)
Where :
1 D = 3.34 X 10 -30 C.m
Dipole moment can not be used to predict / identify :
1.% ionic character
2.Geometry of molecules
3.Cis – trans isomers
4.Limiting reactant
Answer ) Limiting reactant
Brief Explanation :
Dipole moment can be used to predict % ionic character, the geometry of molecules and also identify cis – trans isomers.
A tetra atomic molecule with zero dipole moment is:
1.Bent
2.Pyramidal
3.Unsymmetrical
4.Planar Trigonal
Answer ) Planar Trigonal
Brief Explanation :
Tetra atomic molecules like BF3, BH3 etc with zero dipole moment have planar Trigonal shapes.
The different bond moments cancel out each other effect and the resultant dipole moment is zero.
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