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Chemical Bonding and Molecular Structure

Multiple Choice Questions

371.

Which one of the following molecules has the least dipole moment?

H₂O
BeF₂
NH₃
NF₃

372.

Dipole-dipole interaction energy between polar molecules in solids depends on the radius of the molecule (r) and it is directly proportional to

(1/r³)
(1/r⁶)
(1/r)
(1/r⁵)

373.

Which of the following changes in the respective bond order values are caused by removal of an electron from N₂ and F₂ molecules?

Decrease by 0.5 in both
Increase by 0.5 in both
Increase by 0.5 in the former and decrease by 0.5 in the latter
Decrease by 0.5 in the former and increase by 0.5 in the latter

374.

The hybridised state of bromine in bromine pentafluoride is

sp³d
dsp³
d²sp³
sp³d²

375.

The correct ascending order of ligand field strength of the given ligands is

F^- < I^- < CN^- < H₂O < CO
I^- < F^- < H₂O < CO < CN^-
I^- < F^- < H₂O < CN^- < CO
F^- < H₂O < I^- < CN^- < CO

376.
Arrange the following species in the correct order of their stability
C₂, Li₂, O $_{2}^{+}$ , He $_{2}^{+}$

Li₂ < He $_{2}^{+}$ < O $_{2}^{+}$ < C₂

C₂ < O $_{2}^{+}$ < Li₂ < He $_{2}^{+}$

He $_{2}^{+}$ < Li₂ < C₂ < O $_{2}^{+}$

O $_{2}^{+}$ < C₂ < Li₂ < He $_{2}^{+}$

He $_{2}^{+}$ < Li₂ < C₂ < O $_{2}^{+}$

Higher the bond order, more is the stability. The bond order of the given species can be calculated as-

MO configuration of C₂ = (6 + 6 = 12)

= σ1s², σ*1s², σ2s², σ*2s², $π 2 p_{x}^{2} \approx π 2 p_{y}^{2}$

BO = $\frac{N_{b} - N_{a}}{2} = \frac{8 - 4}{2} = \frac{4}{2} = 2$

MO configuration of Li₂ = (3 + 3 = 6)

= σ1s², σ*1s², σ2s²

BO = $\frac{4 - 2}{2}$ = 1

MO configuration of O₂ = (8 + 8 -1 = 15)

= σ1s², σ*1s², σ2s², σ*2s², σ2p $_{z}^{2}$ , $π 2 p_{x}^{2} \approx π 2 p_{y}^{2}, π * 2 p_{x}^{1}$

BO = $\frac{2 - 1}{2} = \frac{1}{2} = 0.5$

Thus, the order of bond orders of the given species is

He $_{2}^{+}$ < Li₂ < C₂ < O $_{2}^{+}$

Since, bond order α stability.

Thus, order of stability will also be the same.

377.

Molecular formulae and shapes of some molecules are given below. Choose the incorrect match.

NH₃ - Trigonal pyramidal
SF₄ - Tetrahedral
ClF₃ - T-shaped
PCl₅ - Triginal bipyramidal

378.

In which one of the following the central atom is sp³ hydridised?

NH $_{4}^{+}$
BF₃
SF₆
PCl₅

379.

The calculated magnetic moment of a divalent ion of an atom with atomic number 24 in aqueus solution is

4.90 BM
5.92 BM
3.87 BM
2.84 BM

380.

Molecular shapes of SF₄ ,CF₄ and XeF₄ and the number of lone pairs on the central atom are respectively

the same, with 1, 2 and 1
the same with 1, 0 and 1
different with 0, 1 and 2
different with 1, 0 and 2

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Multiple Choice Questions

376. Arrange the following species in the correct order of their stabilityC2, Li2, O2+, He2+ Li2 < He2+ < O2+ < C2 C2 < O2+ < Li2 < He2+ He2+ < Li2 < C2 < O2+ O2+ < C2 < Li2 < He2+

376.
Arrange the following species in the correct order of their stability
C₂, Li₂, O $_{2}^{+}$ , He $_{2}^{+}$

Li₂ < He $_{2}^{+}$ < O $_{2}^{+}$ < C₂

C₂ < O $_{2}^{+}$ < Li₂ < He $_{2}^{+}$

He $_{2}^{+}$ < Li₂ < C₂ < O $_{2}^{+}$

O $_{2}^{+}$ < C₂ < Li₂ < He $_{2}^{+}$