Q: Which of the following best describes the vector sum of bond dipole moments in a molecule of BF$_3$?

The vector sum is zero, so the molecule is nonpolar.

Q: Which of the following correctly ranks the repulsions in order from largest to smallest, affecting bond angles in a molecule?

Lone pair > triple bond > double bond > single bond

Question 1

According to VSEPR theory, what is the electron domain geometry and approximate bond angle for a molecule with three electron groups around the central atom and no lone pairs?

Accepted Answer

Trigonal planar, $120^\circ$

Question 2

Which of the following molecules is expected to have a bent molecular geometry due to the presence of lone pairs on the central atom?

Accepted Answer

H$_2$O

Question 3

A molecule of SF$_6$ has six electron groups around the central atom. What is its molecular geometry and the ideal bond angle?

Accepted Answer

Octahedral, $90^\circ$

Question 4

Which of the following statements 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 than bonding pairs, compressing the bond angle.

Question 5

In the molecule PCl$_5$, where should a lone pair be placed to minimize repulsion according to VSEPR theory?

Accepted Answer

In an equatorial position

Question 6

Which of the following molecules is nonpolar despite having polar bonds?

Accepted Answer

CO$_2$

Question 7

A molecule has four electron groups: two bonding pairs and two lone pairs. What is its molecular geometry and approximate bond angle?

Accepted Answer

Bent, $<109.5^\circ$

Question 8

Which of the following best describes the vector sum of bond dipole moments in a molecule of BF$_3$?

Accepted Answer

The vector sum is zero, so the molecule is nonpolar.

Question 9

Which of the following correctly ranks the repulsions in order from largest to smallest, affecting bond angles in a molecule?

Accepted Answer

Lone pair > triple bond > double bond > single bond

Question 10

Methanol (CH$_3$OH) has two central atoms: carbon and oxygen. What are the molecular geometries around each, respectively?

Accepted Answer

Tetrahedral (C), bent (O)

Question 11

Which of the following molecules will have a net molecular dipole moment?

Accepted Answer

CH$_3$Cl

Question 12

A molecule has five electron groups: three bonding pairs and two lone pairs. What is its molecular geometry?

Accepted Answer

T-shaped

Question 13

Which of the following best describes the bond angles in water (H$_2$O)?

Accepted Answer

Less than $109.5^\circ$ due to two lone pairs on oxygen

Question 14

Which of the following is the correct formula for the bond dipole moment ($\mu$)?

Accepted Answer

$\mu = Qr$

Question 15

In a molecule with octahedral electron geometry and two lone pairs, what is the resulting molecular geometry?

Accepted Answer

Square planar

Question 16

Which of the following best explains why CO$_2$ is nonpolar even though it contains polar bonds?

Accepted Answer

The bond dipole moments are equal in magnitude and opposite in direction, so they cancel.

Question 17

Which of the following molecules has a trigonal bipyramidal electron geometry but a seesaw molecular geometry?

Accepted Answer

SF$_4$

Question 18

A molecule has six electron groups: four bonding pairs and two lone pairs. According to VSEPR theory, what is its molecular geometry?

Accepted Answer

Square planar

Question 19

Which of the following best describes the process for predicting the 3D structure of a molecule using VSEPR theory?

Accepted Answer

Draw the Lewis structure, count electron groups, determine geometry, and use line-dash-wedge notation.

Question 20

Which of the following molecules is expected to have a net dipole moment pointing toward the more electronegative atom?

Accepted Answer

HCl

Covalent Bonding II: Molecular Shapes, VSEPR Theory, and Molecular Polarity (Ch. 10)

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