Question 1

Which statement best explains why the CO$$_2$$ molecule is nonpolar, even though each C–O bond is polar?

Accepted Answer

The molecule is linear, so the bond dipoles cancel each other out, resulting in no net molecular dipole.

Question 2

Given the electronegativity values $$C = 2.6$$ and $$O = 3.5$$, what type of bond is formed between carbon and oxygen in CO$$_2$$?

Accepted Answer

Polar covalent

Question 3

Which molecule carries a large molecular dipole?

Accepted Answer

Formaldehyde (H$$_2CO)$$

Question 4

What is the correct sequence of steps for drawing a Lewis structure for a simple organic molecule?

Accepted Answer

Determine the number of valence electrons, arrange atoms (least electronegative in center), connect atoms by single bonds, arrange remaining electrons to complete octet.

Question 5

Which of the following molecules is an exception to the octet rule and is stable with only 6 valence electrons?

Accepted Answer

Boron trifluoride (BF$$_3)$$

Question 6

How many valence electrons are present in the Lewis structure of formaldehyde (H$$_2CO$$)?

Accepted Answer

$$12$$

Question 7

Which functional group is present in both acetone and formaldehyde?

Accepted Answer

Carbonyl group ($$C=O)$$

Question 8

In bond-line notation, how many hydrogen atoms are attached to a carbon atom that is shown with two bonds?

Accepted Answer

$$2$$

Question 9

Which of the following best describes the molecular geometry and bond angles of a carbon atom with $$sp^2$$ hybridization?

Accepted Answer

Trigonal planar, $$120^	ext{o}$$ bond angles

Question 10

Which of the following molecules would you expect to have a net molecular dipole?

Accepted Answer

Formaldehyde (H$$_2CO)$$

Question 11

What is the formal charge on the central carbon atom in the carbonate ion ($$CO_3$$^{2-}$$)?

Accepted Answer

$$0$$

Question 12

Which functional group is present in phenol?

Accepted Answer

Hydroxyl group ($$-OH) $$attached to an aromatic ring

Question 13

Which of the following best describes the difference between a molecular dipole and a bond dipole?

Accepted Answer

A bond dipole is the separation of charge between two atoms in a bond, while a molecular dipole is the vector sum of all bond dipoles in a molecule.

Question 14

Which of the following molecules is correctly classified as an ether?

Accepted Answer

Diethyl ether ($$CH_3CH_2OCH_2CH_3)$$

Question 15

Which of the following is a correct statement about the bond-line notation for organic molecules?

Accepted Answer

Hydrogen atoms attached to carbon are usually omitted, but all heteroatoms and their hydrogens must be shown.

Question 16

Which of the following functional groups contains a nitrogen atom directly bonded to a carbonyl carbon ($$C=O$$)?

Accepted Answer

Amide

Question 17

A molecule contains a $$C=C$$ triple bond. Which functional group does it belong to?

Accepted Answer

Alkyne

Question 18

Which of the following is true about the formal charge calculation for an atom in a Lewis structure?

Accepted Answer

Formal charge = (valence electrons in free atom) - (unshared electrons + half of shared electrons)

Question 19

Which of the following molecules can expand its valence shell to accommodate more than 8 electrons?

Accepted Answer

Sulfur hexafluoride (SF$$_6)$$

Question 20

Which of the following is the correct IUPAC name for a molecule with the structure $$CH_3CH_2OH$$?

Accepted Answer

Ethanol

Fundamentals of Covalent Bonding, Molecular Polarity, and Lewis Structures in Organic Chemistry

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