Question 1

Which of the following statements best explains why the bond angle in H$$_2S is $$approximately 92°, rather than the 109.5° predicted by simple VSEPR theory for four electron pairs?

Accepted Answer

The S atom in H$$_2S $$uses pure p orbitals for bonding, which are oriented at 90°, and the bond angle is slightly increased by electron pair repulsion.

Question 2

Which of the following molecules requires the use of d orbitals in its hybridization to explain its observed geometry?

Accepted Answer

SF$$_6$$

Question 3

A molecule has a central atom with three bonding pairs and one lone pair. According to VSEPR theory, what is the electron domain geometry and the expected hybridization of the central atom?

Accepted Answer

Tetrahedral geometry; sp$$^3$$ hybridization

Question 4

Which of the following best describes the bonding in C$$_2H$_2 ($$acetylene)?

Accepted Answer

Each carbon is sp hybridized, forming one sigma bond with the other carbon and two pi bonds from unhybridized p orbitals.

Question 5

Which of the following statements about sigma (σ) and pi (π) bonds is correct?

Accepted Answer

A double bond consists of one sigma bond and one pi bond.

Question 6

In the molecule BF$$_3$$, what is the hybridization of the boron atom, and what is the geometry of the molecule?

Accepted Answer

sp$$^2$$ hybridization; trigonal planar geometry

Question 7

Which of the following best explains why BeCl$$_2 is $$linear, even though Be has no unpaired electrons in its ground state?

Accepted Answer

Be promotes an electron and forms two sp hybrid orbitals, which arrange linearly at 180°.

Question 8

Which of the following molecules has a central atom with sp$$^3d$^2$$ hybridization?

Accepted Answer

SF$$_6$$

Question 9

A molecule has five electron domains around its central atom. What is the expected hybridization and electron domain geometry?

Accepted Answer

sp$$^3d $$hybridization; trigonal bipyramidal geometry

Question 10

Which of the following is a limitation of VSEPR theory that is addressed by Valence Bond Theory and hybridization?

Accepted Answer

VSEPR cannot explain why BeCl$$_2 is $$linear, but hybridization shows Be forms two sp orbitals oriented 180° apart.

Question 11

Which of the following best explains why the bond angle in NH$$_3 is $$less than the ideal tetrahedral angle?

Accepted Answer

The lone pair on nitrogen exerts greater repulsion on the bonding pairs, compressing the bond angle.

Question 12

Which of the following correctly matches the molecule with the hybridization of its central atom and the number of sigma and pi bonds between the central atom and its neighbors?

Accepted Answer

CH$$_2O$$: C is sp$$^2$$ hybridized; forms three sigma bonds and one pi bond.

Question 13

Which of the following is true about the formation of hybrid orbitals?

Accepted Answer

Hybrid orbitals are formed by mixing atomic orbitals on the same atom to create equivalent orbitals oriented for bonding.

Question 14

Which of the following best describes the bonding in F$$_2$$?

Accepted Answer

A sigma bond is formed by the end-to-end overlap of two half-filled 2p orbitals, one from each F atom.

Question 15

Which of the following molecules would you expect to have restricted rotation around its central bond due to the presence of a pi bond?

Accepted Answer

C$$_2H$_4 ($$ethylene)

Question 16

A central atom forms four sigma bonds and has no lone pairs. What is the expected hybridization and geometry?

Accepted Answer

sp$$^3$$ hybridization; tetrahedral geometry

Question 17

Which of the following steps is NOT part of the procedure for determining the hybridization of a central atom?

Accepted Answer

Measuring the bond enthalpy of the molecule.

Question 18

Which of the following is a correct statement about the relationship between VSEPR theory and Valence Bond Theory?

Accepted Answer

VSEPR predicts the arrangement of electron domains, while Valence Bond Theory explains the formation and orientation of bonds using hybrid orbitals.

Question 19

Which of the following molecules has a central atom with two lone pairs and two bonding pairs, and what is the expected bond angle?

Accepted Answer

H$$_2O$$; bond angle is approximately 105°

VSEPR Theory, Valence Bond Theory, and Hybridization: Molecular Shapes and Bonding

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