Question 1

Which of the following molecules has a central atom with sp2 hybridization, and what is the expected bond angle around the central atom?

Accepted Answer

BF3; $$120^\circ$$

Question 2

Given the following data for H-F: bond length = 91.7 pm, dipole moment = 1.83 D, and using $$e = 1.6 	imes 10$$^{-19}$$ C, 1$ D = 3.33$$ 	imes $$10^{-30} C$$·m, calculate the percent ionic character of the H-F bond. (Use $$\mu = \delta e d$$ and assume $$d in $$meters.)

Accepted Answer

$$\approx 41\%$$

Question 3

Which of the following best describes the difference between a sigma ($$\sigma) $$bond and a pi ($$\pi) $$bond?

Accepted Answer

$$\sigma$$ bonds result from head-on overlap of orbitals, while $$\pi$$ bonds result from sidewise overlap.

Question 4

Which molecule is planar and exhibits resonance due to delocalized $$\pi$$ electrons?

Accepted Answer

C6H6 (benzene)

Question 5

What is the hybridization of the central atom in SF6, and what is the molecular geometry?

Accepted Answer

sp3d2; octahedral

Question 6

Which of the following statements about isomers is correct?

Accepted Answer

Isomers have the same molecular formula but different arrangements of atoms.

Question 7

In the molecule C2H4 (ethylene), what is the hybridization of each carbon atom and the geometry around each carbon?

Accepted Answer

sp2; trigonal planar

Question 8

Which of the following best explains why rotation around a double bond is restricted, leading to geometric isomerism?

Accepted Answer

The presence of a $$\pi$$ bond prevents free rotation.

Question 9

What is the expected bond angle in BeCl2, and what is the hybridization of the central atom?

Accepted Answer

$$180^\circ$$; sp

Question 10

Which of the following molecules is expected to be nonpolar, despite having polar bonds?

Accepted Answer

BF3

Question 11

Which of the following best describes the difference between conformers and isomers?

Accepted Answer

Conformers can be interconverted by rotation around single bonds, while isomers require breaking covalent bonds.

Question 12

Which of the following molecules has a central atom with sp3d hybridization and what is its geometry?

Accepted Answer

PF5; trigonal bipyramidal

Question 13

Which of the following statements about the chair conformation of cyclohexane is correct?

Accepted Answer

The chair conformation is more stable due to minimized torsional strain.

Question 14

Which of the following is the correct electron configuration for Zn (Z = 30)?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$ $$3d^{10}$$

Question 15

Which of the following molecules has a central atom with sp3 hybridization and a bond angle closest to $$109.5^\circ$$?

Accepted Answer

CH4

Question 16

Which of the following best explains why NH3 has a bond angle less than $$109.5^\circ$$?

Accepted Answer

Lone pair-bond pair repulsion is greater than bond pair-bond pair repulsion.

Question 17

Which of the following molecules is expected to have the highest dipole moment?

Accepted Answer

NaCl

Question 18

Which of the following is a correct statement about the hybridization of the central atom in CO32-?

Accepted Answer

The central atom is sp2 hybridized.

Question 19

Which of the following best describes the geometry and hybridization of the central atom in ICl4-?

Accepted Answer

Square planar; sp3d2

Valence Bond Theory, Hybridization, and Molecular Geometry

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