Question 1

According to VSEPR theory, what is the bond angle in a molecule with a tetrahedral geometry, such as methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

$$109.5^\circ$$

Question 2

Which of the following best explains why lone pairs occupy more space than bonding pairs in a molecule?

Accepted Answer

Lone pairs are not attracted to another nucleus and are drawn closer to the central atom, causing greater repulsion.

Question 3

What is the molecular shape and approximate bond angle of ammonia ($$\mathrm{NH_3$}$$)?

Accepted Answer

Trigonal pyramidal, $$107^\circ$$

Question 4

Which of the following molecules is linear according to VSEPR theory?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 5

A molecule of water ($$\mathrm{H_2O}) $$has two bonding pairs and two lone pairs on the central atom. What is its molecular geometry and bond angle?

Accepted Answer

Bent, $$104.5^\circ$$

Question 6

Which statement correctly distinguishes between intramolecular and intermolecular forces?

Accepted Answer

Intramolecular forces hold atoms together within a molecule, while intermolecular forces act between molecules.

Question 7

How many regions of electron density are around the central atom in carbon dioxide ($$\mathrm{CO_2$}$$), and what is the resulting shape?

Accepted Answer

Two regions, linear

Question 8

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

Accepted Answer

Lone pairs decrease the bond angle between bonding pairs.

Question 9

A molecule has three regions of electron density and no lone pairs on the central atom. What is its molecular geometry and bond angle?

Accepted Answer

Trigonal planar, $$120^\circ$$

Question 10

Which of the following molecules would be expected to have a bent (V-shaped) geometry?

Accepted Answer

$$\mathrm{H_2O}$$

Question 11

In the context of VSEPR theory, how are double and triple bonds treated when determining molecular shape?

Accepted Answer

Each double or triple bond is counted as a single region of electron density.

Question 12

Which of the following real-world scenarios best illustrates the importance of molecular shape in biological systems?

Accepted Answer

The specific shape of an enzyme allows it to bind only to its substrate, enabling biological catalysis.

Question 13

Which molecule has a trigonal planar geometry?

Accepted Answer

$$\mathrm{BF_3$}$$

Question 14

A student draws the Lewis structure for $$\mathrm{F_2$}$$ and counts six lone pairs and one bonding pair. What does this indicate about the electron dot diagram?

Accepted Answer

There are six lone pairs (three on each F) and one bonding pair between the two F atoms.

Question 15

Which of the following statements about the effect of lone pairs on molecular geometry is correct?

Accepted Answer

Lone pairs are not included when describing the shape, but they do affect the positions of the bonding pairs.

Question 16

Which of the following best describes the difference between a Lewis structure and a stick model of a molecule?

Accepted Answer

A Lewis structure shows all valence electrons, while a stick model represents the 3D geometry and bond angles.

Question 17

Which of the following molecules would you expect to have a bond angle closest to $$120^\circ$$?

Accepted Answer

$$\mathrm{BF_3$}$$

Question 18

A molecule has four regions of electron density: two bonding pairs and two lone pairs. What is its molecular geometry?

Accepted Answer

Bent

Question 19

Which of the following is a correct application of VSEPR theory to predict the shape of hydrogen sulfide ($$\mathrm{H_2S}$$)?

Accepted Answer

It is bent because it has two bonding pairs and two lone pairs on sulfur.

Question 20

Which of the following best explains why $$\mathrm{CO_2$} is a $$linear molecule, even though it contains double bonds?

Accepted Answer

Each double bond is counted as one region of electron density, and two regions arrange themselves $$180^\circ$$ apart.

Molecular Shapes and VSEPR Theory in Organic Chemistry

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