part 1: multiple choice questions
1. what does vsepr stand for?
a. valence shell electron pair repulsion
b. very strong electron pair reaction
c. variable shape energy pair repulsion
d. valence shell energy proton repulsion
2.**which molecule has a trigonal planar shape? (hint! draw out the lewis dot diagram for reach molecule)
a. h₂o
b. bf₃
c. nh₃
d. ch₄
3.*how many electron regions are around the central atom in ch₄?
a. 2
b. 3
c. 4
d. 5
4.**which factor causes bent shapes to have smaller bond angles?
a. double bonds
b. lone pair repulsion
c. heavy atoms
d. symmetry
part 2: true or false
note: if the answer is false, write the correct answer.
5. lone pairs repel more strongly than bonding pairs.
if false, explain:
6. **a molecule with 3 bonding regions and 1 lone pair has a trigonal planar shape.
if false, explain:
7. **nh₃ has bond angles close to 120°.
if false, explain:
8. *co₂ has a linear shape with 180° bond angles.
if false, explain:
part 3: identify the shape & angle
instructions: determine the molecular shape and approximate bond angle for each of the following molecules.
molecule bonding pairs lone pairs lewis dot diagram shape bond angle
*ch₄ 4 0
**nh₃ 3 1
**h₂o 2 2
*co₂ 2 0
bf₃ 3 0

Question

part 1: multiple choice questions
1. what does vsepr stand for?
a. valence shell electron pair repulsion
b. very strong electron pair reaction
c. variable shape energy pair repulsion
d. valence shell energy proton repulsion
2.**which molecule has a trigonal planar shape? (hint! draw out the lewis dot diagram for reach molecule)
a. h₂o
b. bf₃
c. nh₃
d. ch₄
3.*how many electron regions are around the central atom in ch₄?
a. 2
b. 3
c. 4
d. 5
4.**which factor causes bent shapes to have smaller bond angles?
a. double bonds
b. lone pair repulsion
c. heavy atoms
d. symmetry
part 2: true or false
note: if the answer is false, write the correct answer.
5. lone pairs repel more strongly than bonding pairs.
   if false, explain:
6. **a molecule with 3 bonding regions and 1 lone pair has a trigonal planar shape.
   if false, explain:
7. **nh₃ has bond angles close to 120°.
   if false, explain:
8. *co₂ has a linear shape with 180° bond angles.
   if false, explain:
part 3: identify the shape & angle
instructions: determine the molecular shape and approximate bond angle for each of the following molecules.
molecule bonding pairs lone pairs lewis dot diagram shape bond angle
*ch₄ 4 0
**nh₃ 3 1
**h₂o 2 2
*co₂ 2 0
bf₃ 3 0

Accepted Answer

### Part 1: Multiple Choice Questions

#### Question 1
# Brief Explanations:
VSEPR is a theory to predict molecular shapes, and its full name is Valence Shell Electron Pair Repulsion.
# Answer:
A. Valence Shell Electron Pair Repulsion

#### Question 2
# Brief Explanations:
- $ \ce{H2O} $: 2 bonding pairs, 2 lone pairs → bent.
- $ \ce{BF3} $: 3 bonding pairs, 0 lone pairs → trigonal planar.
- $ \ce{NH3} $: 3 bonding pairs, 1 lone pair → trigonal pyramidal.
- $ \ce{CH4} $: 4 bonding pairs, 0 lone pairs → tetrahedral.
# Answer:
B. $ \ce{BF3} $

#### Question 3
# Brief Explanations:
In $ \ce{CH4} $, the central C atom has 4 single bonds (bonding pairs) with H atoms, so there are 4 electron regions.
# Answer:
C. 4

#### Question 4
# Brief Explanations:
Lone pairs repel more strongly than bonding pairs, causing bent molecules (e.g., $ \ce{H2O} $) to have smaller bond angles than idealized shapes. Double bonds, heavy atoms, or symmetry do not explain this.
# Answer:
B. Lone pair repulsion

### Part 2: True or False

#### Question 5
# Brief Explanations:
Lone pairs (non - bonding electron pairs) have a stronger repulsive force than bonding pairs (electron pairs involved in bonds) because lone pairs are more concentrated around the central atom.
# Answer:
True

#### Question 6
# Brief Explanations:
A molecule with 3 bonding regions and 1 lone pair has a trigonal pyramidal shape (e.g., $ \ce{NH3} $), not trigonal planar (trigonal planar has 3 bonding regions and 0 lone pairs).
# Answer:
False
If False, explain: A molecule with 3 bonding regions and 1 lone pair has a trigonal pyramidal shape (e.g., $ \ce{NH3} $). Trigonal planar requires 3 bonding regions and 0 lone pairs.

#### Question 7
# Brief Explanations:
$ \ce{NH3} $ has a trigonal pyramidal shape with bond angles close to $ 107^\circ $, not $ 120^\circ $ ( $ 120^\circ $ is typical for trigonal planar, like $ \ce{BF3} $ ).
# Answer:
False
If False, explain: $ \ce{NH3} $ has a trigonal pyramidal shape with bond angles close to $ 107^\circ $, not $ 120^\circ $.

#### Question 8
# Brief Explanations:
$ \ce{CO2} $ has a linear shape with the central C atom double - bonded to two O atoms ( $ \ce{O = C = O} $ ). There are no lone pairs on the central C, so the bond angle is $ 180^\circ $.
# Answer:
True

### Part 3: Identify the Shape & Angle

We use the VSEPR theory: the molecular shape is determined by the number of bonding pairs and lone pairs around the central atom.

| Molecule | Bonding Pairs | Lone Pairs | Shape          | Bond Angle       |
|----------|---------------|------------|----------------|------------------|
| $ \ce{CH4} $ | 4             | 0          | Tetrahedral    | $ 109.5^\circ $ |
| $ \ce{NH3} $ | 3             | 1          | Trigonal Pyramidal | $ 107^\circ $   |
| $ \ce{H2O} $ | 2             | 2          | Bent           | $ 104.5^\circ $ |
| $ \ce{CO2} $ | 2             | 0          | Linear         | $ 180^\circ $   |
| $ \ce{BF3} $ | 3             | 0          | Trigonal Planar | $ 120^\circ $   |

For the Lewis Dot Diagrams:
- $ \ce{CH4} $: C in the center with 4 single bonds to H atoms, each H has 1 electron pair from the bond.
- $ \ce{NH3} $: N in the center with 3 single bonds to H atoms and 1 lone pair on N.
- $ \ce{H2O} $: O in the center with 2 single bonds to H atoms and 2 lone pairs on O.
- $ \ce{CO2} $: C in the center with 2 double bonds to O atoms ( $ \ce{O = C = O} $ ), each O has 2 lone pairs.
- $ \ce{BF3} $: B in the center with 3 single bonds to F atoms, each F has 3 lone pairs.

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Part 1: Multiple Choice Questions

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Question 2