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a lone pair refers to a pair of valence electrons that are not shared with another atom and is sometimes called an unshared pair or non-bonding pair. Lone pairs are found in the outermost electron shell of atoms. They can be identified by using a Lewis structure.
Engineering
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The decreasing order of bond angles in BF3, NH3, PF3 and I_{3}^{-}is :

  • Option 1)

    I_{3}^{-} > NH_{3}> PF_{3}> BF_{3}

     

     

     

  • Option 2)

    I_{3}^{-} >BF_{3}> NH_{3}> PF_{3}

  • Option 3)

    BF_{3} >I_{3}^{-}}>PF_{3}>NH_{3}

  • Option 4)

    BF_{3} >NH_{3}>PF_{3}>I_{3}^{-}}

 
As we learned    S - P Hybridisation - When one S - and one P - orbital belonging to the same main shell of an atom are mixed together to form two new SP - orbitals. - wherein shapes            Diagonal or Linear     sp2 Hybridisation - When one s - and two p - orbitals of the same shell of an atom mix to form three new equivalent orbitals.The hybridised orbital is called sp2 orbital. -...
Engineering
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             (I)      (II)

H –– N - - - N - - - N

In hydrogen azide (above) the bond orders of bonds (I) and (II) are :

  • Option 1)

         (I)              (II)

    < 2\; \; \; \; \; \; \; > 2

     

     

     

  • Option 2)

    > 2\; \; \; \; \; \; \; < 2

  • Option 3)

    > 2\; \; \; \; \; \; \; > 2

  • Option 4)

    < 2\; \; \; \; \; \; \; < 2

 
As we learned    Bond Order - Bond order is defined as one half the difference between the number of electrons present in the bonding and the antibonding orbitals. - wherein       Option 1)      (I)              (II)       Option 2) Option 3) Option 4)
Engineering
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In the molecular orbital diagram for the molecular ion, N_{2}^{+},  the number of electrons in the \sigma_{2p} molecular orbital is :

  • Option 1)

    0

  • Option 2)

    1

  • Option 3)

    2

  • Option 4)

    3

 

As we learned

 

Molecular Orbital Theory ( M.O.T ) -

Molecular orbital ( M.O ) Theory was developed by F Hund and  R.S Mulliken in 1932.

-

 

 N_{2}^{+}\rightarrow \sigma _{132}, \sigma _{182}, \sigma _{252},\sigma _{252} [\pi _{2px}^{2}=\pi _{2py}^{2}=]\sigma _{2p}^{1}

Number of electrons in\sigma _{2pa}=1


Option 1)

0

Option 2)

1

Option 3)

2

Option 4)

3

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Engineering
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Total number of lone pair of electrons in   I_{3}^{-}  ion is :

  • Option 1)

    12

  • Option 2)

    3

  • Option 3)

    6

  • Option 4)

    9

 

As we learn

Lewis structure -

1. pair of bonded electrons is by means of a dash (-) usually called a bond 

2. Lone pairs or non-bonded electrons are represented by dots

3. Electron represent in the last shell of atoms are called valence electrons. 

- wherein

 

 

No. of lone pairs =9


Option 1)

12

Option 2)

3

Option 3)

6

Option 4)

9

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Engineering
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According to molecular orbital theory, which of the following will not be a viable molecule?

  • Option 1)

    H_{2}^{2-}
     

  • Option 2)

    He_{2}^{2+}

  • Option 3)

    He_{2}^{+}

     

  • Option 4)

    H_{2}^{-}

 

As we learned

Molecular Orbital Theory ( M.O.T ) -

Molecular orbital ( M.O ) Theory was developed by F Hund and  R.S Mulliken in 1932.

-

 

 H_{2}^{2-}= \sigma _{1s}^{2}\: \sigma _{1s}^{*2}\: \: B.O.= 0


Option 1)

H_{2}^{2-}
 

Option 2)

He_{2}^{2+}

Option 3)

He_{2}^{+}

 

Option 4)

H_{2}^{-}

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Engineering
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In XeO3F2 , the number of bond pair(s),
\pi-bond(s) and lone pair(s) on Xe atom
respectively are :

  • Option 1)

    5, 2, 0

  • Option 2)

    4, 2, 2

  • Option 3)

    5, 3, 0

  • Option 4)

    4, 4, 0

 
As we have learnt,   Dettermination of shape of molecules using VSEPR Theory - -       5 sigma bond, 3  bonds & zero lone pair in Xe. Option 1) 5, 2, 0 Option 2) 4, 2, 2 Option 3) 5, 3, 0 Option 4) 4, 4, 0
Engineering
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Which of the following best describes the
diagram below of a molecular orbital ?

  • Option 1)

    A non-bonding orbital

  • Option 2)

    An antibonding \sigma orbital

  • Option 3)

    A bonding \pi orbital

  • Option 4)

    An antibonding \pi orbital

 
As we have learnt,   Bonding and Antibonding molecular orbital -                             is called bonding molecular orbital                           is called antibonding molecular orbital -     is describing the antibonding -orbitial Option 1) A non-bonding orbital Option 2) An antibonding orbital Option 3) A bonding  orbital Option 4) An antibonding  orbital
Engineering
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The most polar compound among the following is :

  • Option 1)

  • Option 2)

  • Option 3)

  • Option 4)

 
As we have learned Resultant dipole moment - Let XY and XZ are two polar bonds inclined at an angle  their dipole moments are    - wherein           In       the bond dipole vector of C-F bond is not subtractive Option 1) This is correct Option 2) This is incorrect Option 3) This is incorrect Option 4) This is incorrect
Engineering
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A group 13 element ‘X’ reacts with chlorine gas to produce a compoundXCl_{3}.  XCl_{3} is electron deficient and easily reacts with NH_{3} to form Cl_{3 }\leftarrow NH_{3} adduct;
however, XCl_{3} does not dimerize. X is :

  • Option 1)

    B

  • Option 2)

    Al

  • Option 3)

    Ga

  • Option 4)

    In

 
As we have learned Pi bond - This type of bond is formed by sidewise or lateral over lapping of two half filled atomic orbitals. - wherein    can not dimense due to   back bonding    Option 1) B This is correct Option 2) Al This is incorrect Option 3) Ga This is incorrect Option 4) In This is incorrect
Engineering
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Which of the following conversions involves change in both shape and hybridisation ?

  • Option 1)

    NH_{3}\rightarrow NH_{4}^{+}

  • Option 2)

    CH_{4}\rightarrow C_{2}H_{6}

  • Option 3)

    H_{2O \rightarrow }H_{3}O^{+}

  • Option 4)

    BF_{3}\rightarrow BF_{4}^{-}

 
As we have learned Hybridisation - The process of mixing of atomic orbitals belonging to the same atoms of slightly different energies so that a redistribution of energy takes place between them  resulting in the formation of new set of orbital of equivalent energies and shape is called hybridisation. - wherein The new orbitals thus formed are called hybrid orbitals     Option 1) This is...
Engineering
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The incorrect geometry is represented by :

  • Option 1)

    BF_{3}  - trigonal planar

  • Option 2)

    H_{2}O- bent 

  • Option 3)

    NF_{3}- trigonal planar

  • Option 4)

    AsF_{5}- trigonal bipyramidal

 

As we have learned

Dettermination of shape of molecules using VSEPR Theory -

calculate \:X

X=(No.\;of\:valence\:electrons\:of\:central\:atom\:)+(No.\:of\:other\:atom\:)+(Negative\:charge\:on\:the\:molecule)-(Positive\:charge\:on\:the\:molecule)

-

 

 The geometry of NF_{3} is pyramidal 


Option 1)

BF_{3}  - trigonal planar

This is incorrect

Option 2)

H_{2}O- bent 

This is incorrect

Option 3)

NF_{3}- trigonal planar

This is correct

Option 4)

AsF_{5}- trigonal bipyramidal

This is incorrect

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