$$\text{DU} = \frac{2C + 2 - H}{2}$$

Question 1

Which of the following statements about Lewis structures is CORRECT?

Accepted Answer

Lewis structures are used to determine chemical structures based on the order of valence and bonding preferences.

Question 2

Given the molecule HCO$$_2H ($$formic acid), what is the total number of valence electrons used in its Lewis structure?

Accepted Answer

$$20$$

Question 3

Which condensed structural formula corresponds to the following molecule?

A molecule with a straight chain of five carbons, each bonded to two hydrogens except the terminal carbons, which are bonded to three hydrogens.

Accepted Answer

CH$$_3CH$_2CH$_2CH$_2CH$_3$$

Question 4

How many degrees of unsaturation are present in the molecule C$$_6H$_6$$?

Accepted Answer

$$4$$

Question 5

Which formula is used to calculate the degree of unsaturation from a molecular formula?

Accepted Answer

$$	ext{DU} = \frac{2C + 2 - H}{2}$$

Question 6

Which of the following pairs are constitutional isomers?

Accepted Answer

CH$$_3CH$_2CH$_2CH$_3$$ and CH$$_3CH(CH$_3)CH$_3$$

Question 7

What is the hybridization of the central carbon atom in formaldehyde (CH$$_2O$$)?

Accepted Answer

$$sp^2$$

Question 8

According to VSEPR theory, what is the molecular geometry of a molecule with three regions of electron density and no lone pairs on the central atom?

Accepted Answer

Trigonal planar

Question 9

Which of the following molecules has a linear geometry?

Accepted Answer

CO$$_2$$

Question 10

What is the hybridization and geometry of the oxygen atom in water (H$$_2O$$)?

Accepted Answer

Hybridization: $$sp^3$$, Geometry: Bent

Question 11

A molecule has the formula C$$_4H$_8. $$How many degrees of unsaturation does it have?

Accepted Answer

$$1$$

Question 12

Which statement best describes the difference between a condensed structure and a condensed mixed structure?

Accepted Answer

A condensed structure shows only the carbon backbone, while a condensed mixed structure shows both backbone and functional groups.

Question 13

Which of the following molecules is saturated?

Accepted Answer

C$$_3H$_8$$

Question 14

What is the hybridization of the nitrogen atom in ammonia (NH$$_3$$)?

Accepted Answer

$$sp^3$$

Question 15

Which principle states that electrons fill orbitals in order of increasing energy?

Accepted Answer

Aufbau Principle

Question 16

How many lone pairs are present on the oxygen atom in methanol (CH$$_3OH$$)?

Accepted Answer

$$2$$

Question 17

Which of the following is NOT a step in drawing a Lewis structure?

Accepted Answer

Ignoring the octet rule for second period elements

Question 18

What is the molecular geometry of the central atom in carbon dioxide (CO$$_2$$)?

Accepted Answer

Linear

Question 19

Which of the following molecules has a tetrahedral geometry?

Accepted Answer

CH$$_4$$

Bonding and Molecular Structure: Study Notes for Organic Chemistry

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