Four diatomic species are listed below in different sequences. Wh

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 Multiple Choice QuestionsMultiple Choice Questions

491.

The AsF5 molecule is trigonal bipyramidal. The hybrid orbitals used by the As atoms for bonding are

  • dx2-y2, dz2, s, px, py

  • dxy, s, px, py, pz

  • dx2-y2, s, px, py

  • s, px, py, pz, dz2


492.

Hydride of boron occurs as B2H6 but B2Cl6 does not exist. This is because

  • pπ - dπ back bonding is possible in B2H6 but not in B2Cl6

  • boron and hydrogen have almost equal values of electronegativity

  • boron and chlorine have almost equal atomic sizes

  • small hydrogen atoms can easily fit in between boron atoms but large chlorine atoms do not.


493.

Assertion : trans-Pent-2-ene is polar but trans- but-2-ene is non-polar.

Reason : The polarity of cis-isomer is more than trans-isomer, which are either non-polar or less polar.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false


494.

Assertion : The number of tetrahedral voids is double the number of octahedral voids.

Reason : The size of the tetrahedral voids is half of that of the octahedral void.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false.

  • If both assertion and reason are false.


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495.

Assertion : [Fe(CN)6]3- has d2sp3 type hybridisation.

Reason: [Fe(CN)6]3- ion shows magnetic moment corresponding to two unpaired electrons.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false.


496.

Assertion: Both π(2px) and π*(2px) MO's have one nodal plane.

Reason : All MO's formed by side way overlapping of 2p- orbitals have one nodal plane.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


497.

Which of the following molecules has more than one lone pair ?

  • SO2

  • XeF2

  • SiF4

  • CH4


498.

Each NH3 molecule has six other NH3 molecules as nearest neighbours in solid state ; H of sublimation of NH3 molecule at the m.p. is 30.8 kJ mol-1 and in the absence of H-bonding estimated Ml of sublimation is 14.4 kJ mol-1 .Hence , strength of H-bond in solid NH3 is :

  • 5.47 kJ mol-1

  • 10.93 kJ mol-1

  • 16.40 kJ mol-1

  • - 16.40 kJ mol-1


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499.

Four diatomic species are listed below in different sequences. Which of these represents the correct order of their increasing bond order?

  • C22- < He2+ < NO < O2-

  • He2+ < O2- < NO < C22-

  • O2- < NO < C22- < He2+

  • NO < C22- < O2- < He2+


B.

He2+ < O2- < NO < C22-

According to molecular orbital theory, the energy level of the given molecules are

C22-  σ1s2 σ*1s2 σ2s2 σ*2s2 π2px2 π2py2 σ2pz2

Bond Order : 12[10 - 4] = 3

He2+  σ1s2 σ*1s1

Bond Order : 122 - 1 = 12 = 0.5

 NO  σ1s2 σ*1s2 σ2s2 σ*2s2 σ2pz2 π2px2 π2py2 π*2px1

Bond Order : 1210 - 5 = 2.5

O2-  σ1s2 σ*1s2 σ2s2 σ*2s2 σ2pz2 π2px2 π2py 2π*2px2 π*2py1

Bond Order : 1210 - 7 = 1.5

So, the correct order of their increasing bond order is He2+ < O2- < NO<C22-


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500.

Which one ofthe following is not tetrahedral in shape ?

  • SiCl4

  • NH4+

  • CH4

  • SF4


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