Question 1

Which of the following statements best explains why water (H$$_2O) $$has a bent molecular geometry rather than a linear one?

Accepted Answer

The oxygen atom forms two single bonds with hydrogen atoms, and there are two lone pairs on the oxygen atom, causing repulsion that results in a bent shape.

Question 2

What is the bond angle in a molecule with a tetrahedral electron geometry, such as methane (CH$$_4$$)?

Accepted Answer

$$109.5^\circ$$

Question 3

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

Accepted Answer

Carbon dioxide (CO$$_2)$$

Question 4

A molecule has five electron groups around its central atom, two of which are lone pairs. What is the molecular geometry of this molecule?

Accepted Answer

T-shaped

Question 5

Which vitamin is most likely to dissolve in water based on its molecular structure and polarity?

Accepted Answer

Vitamin C (Ascorbic acid)

Question 6

What is the electron geometry and molecular geometry of SF$$_6$$?

Accepted Answer

Electron geometry: Octahedral; Molecular geometry: Octahedral

Question 7

Which of the following best describes the effect of lone pairs on bond angles in a molecule?

Accepted Answer

Lone pairs decrease the bond angles between bonding pairs due to increased repulsion.

Question 8

A molecule has the Lewis structure shown below. What is the molecular geometry around the central atom?

F—B—F
   |
   F

Accepted Answer

Trigonal planar

Question 9

Which of the following is a necessary condition for a molecule to be polar?

Accepted Answer

The molecule must have polar bonds and an unsymmetrical shape.

Question 10

Which of the following best explains why soap molecules can dissolve both in water and in oil?

Accepted Answer

Soap molecules have both polar and nonpolar regions, allowing them to interact with both water (polar) and oil (nonpolar).

Question 11

What is the bond angle between the axial and equatorial positions in a trigonal bipyramidal geometry?

Accepted Answer

$$90^\circ$$

Question 12

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

Accepted Answer

NH$$_3$$

Question 13

A molecule has six electron groups around the central atom, one of which is a lone pair. What is the molecular geometry?

Accepted Answer

Square pyramidal

Question 14

Which of the following best describes the process of vector addition when determining the net dipole moment in a molecule?

Accepted Answer

Draw vectors for each bond dipole and add them using the parallelogram rule; the resultant vector shows the net dipole moment.

Question 15

Which of the following vitamins is fat-soluble and would be expected to dissolve in nonpolar solvents?

Accepted Answer

Vitamin A (Retinoids)

Question 16

Which of the following best describes the geometry and bond angles of a molecule with three electron groups and one lone pair?

Accepted Answer

Bent geometry with bond angles slightly less than $$120^\circ$$

Question 17

Which of the following molecules has a square planar molecular geometry?

Accepted Answer

XeF$$_4$$

Question 18

Which of the following is the correct sequence of steps for predicting the geometry of a molecule using VSEPR theory?

Accepted Answer

Draw the Lewis structure, count electron groups, classify each group, use VSEPR to determine geometry.

Question 19

Which of the following best explains why vitamin C is water-soluble while vitamin A is fat-soluble?

Accepted Answer

Vitamin C has multiple O-H bonds, making it highly polar and able to hydrogen-bond with water, while vitamin A is mostly nonpolar.

CHEM 131 Chapter 11 Pt. 1: Chemical Bonding II: Molecular Shapes, VSEPR, and Molecular Polarity

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