Class 11 Chemistry Chemical Bonding Important MCQs with Brief Answers for Exams:
A theory that explains the formation of 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 overlapping of half-filled atomic orbitals.
It also explains the strength of a covalent bond in terms of nature and 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 , s-p half-filled atomic orbitals combine from front to front along the same axis to form 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 sides to form 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 sigma bond.
For example , a double or triple bond contain only one sigma bond. Double bond contain 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 which 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 & 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 with 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 , 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 molecule 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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