Question 1

Which of the following bonds is expected to be the most polar based on electronegativity differences?

(a) $$\mathrm{C-H} 
(b$$) $$\mathrm{C-O} 
(c$$) $$\mathrm{C-F} 
(d$$) $$\mathrm{C-Li}$$

Accepted Answer

$$\mathrm{C-F}$$

Question 2

Given the following p$$K_a$$ values: acetic acid ($$pK_a = 4.76$$), methanol ($$pK_a = 15.50$$), and acetylene ($$pK_a = 25$$), which compound is the strongest acid?

Accepted Answer

Acetic acid

Question 3

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

(a) $$\mathrm{CO_2$} 
(b$$) $$\mathrm{CH_4$} 
(c$$) $$\mathrm{$$CHCl_3$$} 
(d$$) $$\mathrm{C_2H_6}$$

Accepted Answer

$$\mathrm{$$CHCl_3$$}$$

Question 4

Which statement best describes the difference between a Brønsted-Lowry acid and a Lewis acid?

Accepted Answer

A Brønsted-Lowry acid donates a proton, while a Lewis acid accepts an electron pair.

Question 5

Which of the following is the correct formula for calculating the dipole moment ($$\mu) of a $$molecule?

Accepted Answer

$$\mu = Q 	imes r$$

Question 6

Which of the following molecules can form hydrogen bonds with water?

(a) $$\mathrm{CH_4$} 
(b$$) $$\mathrm{CH_3OH} 
(c$$) $$\mathrm{C_2H_6} 
(d$$) $$\mathrm{CH_3CH_3}$$

Accepted Answer

$$\mathrm{CH_3OH}$$

Question 7

Which of the following statements about resonance forms is TRUE?

Accepted Answer

The real structure of a molecule is a hybrid of all valid resonance forms.

Question 8

Which atom in the acetate ion ($$\mathrm{CH_3CO_2^-}) $$carries the formal negative charge in its major resonance form?

Accepted Answer

One of the oxygen atoms

Question 9

A student is asked to rank the following bonds in order of increasing polarity: $$\mathrm{C-H}$$, $$\mathrm{C-O}$$, $$\mathrm{C-F}$$, $$\mathrm{C-Li}. $$Which is the correct order?

Accepted Answer

$$\mathrm{C-H} \u003c \mathrm{C-O} \u003c \mathrm{C-Li} \u003c \mathrm{C-F}$$

Question 10

Which of the following is a correct statement about the relationship between $$pK_a$$ and acid strength?

Accepted Answer

A lower $$pK_a$$ means a stronger acid.

Question 11

Which of the following molecules is most likely to be water-soluble due to its ability to form hydrogen bonds?

Accepted Answer

Vitamin C (ascorbic acid)

Question 12

Which of the following is NOT a valid resonance form for the acetate ion ($$\mathrm{CH_3CO_2^-}$$)?

Accepted Answer

A form with a negative charge on the methyl carbon

Question 13

Which of the following best explains why the conjugate base of acetic acid is more stabilized than that of methanol?

Accepted Answer

The negative charge in acetic acid is stabilized by resonance and electronegativity.

Question 14

Which of the following is a correct application of formal charge calculation for oxygen in the methyl phosphate dianion ($$\mathrm{CH_3OPO_3$$^{2-}$$}$$)?

Accepted Answer

Formal charge = 6 - (number of bonding electrons)/2 - number of nonbonding electrons

Question 15

Which of the following intermolecular forces is responsible for the high boiling point of water?

Accepted Answer

Hydrogen bonding

Question 16

Which of the following is a Lewis base in the reaction with boron trifluoride ($$\mathrm{BF_3$}$$)?

Accepted Answer

Dimethyl ether ($$\mathrm{CH_3OCH_3})$$

Question 17

Which of the following statements about the direction of bond polarity is correct?

Accepted Answer

The arrow points from the less electronegative atom to the more electronegative atom.

Question 18

Which of the following molecules contains a three-atom grouping that allows for resonance stabilization of a negative charge?

Accepted Answer

Acetate ion ($$\mathrm{CH_3CO_2^-})$$

Organic Chemistry Chapter 2: Polar Covalent Bonds, Acids, and Bases

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