chemical bonding

Class 11 Chemistry Chapter Chemical Bonding Important MCQs for Exams

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:

Trigonal Planar shape

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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