Q: Which of the following compounds is most likely to be soluble in water, and why?

Vitamin C, because it has several $$-\text{OH}$$ groups that can form hydrogen bonds with water.

Question 1

Which of the following statements best explains why the C–O bond in methanol is polar covalent, while the C–H bond is considered relatively nonpolar?

Accepted Answer

The electronegativity difference between C and O is much greater than between C and H.

Question 2

Given the following electronegativity values: C = 2.5, O = 3.5, H = 2.1, which bond is expected to have the greatest ionic character?

Accepted Answer

$$	ext{O–Li}$$

Question 3

Which molecule below has a zero dipole moment due to its symmetry?

Accepted Answer

$$	ext{CO}_2$$

Question 4

Calculate the formal charge on the sulfur atom in dimethyl sulfoxide ($$	ext{(CH}_3)_2	ext{SO}) $$using the formula:

$$	ext{Formal charge} = 	ext{Valence electrons} - \frac{1}{2}(	ext{Bonding electrons}) - 	ext{Nonbonding electrons}$$

Accepted Answer

$$+1$$

Question 5

Which of the following is NOT a valid resonance form for the acetate ion ($$	ext{CH}_3	ext{CO}_2^-$$)?

Accepted Answer

A structure with both oxygens having a single bond to carbon and each carrying a negative charge.

Question 6

Which of the following statements about resonance hybrids is correct?

Accepted Answer

The resonance hybrid is more stable than any individual resonance form.

Question 7

Which of the following acids is the strongest, based on their pKa values?

$$	ext{p}K_a(	ext{H}_2	ext{O}) = 15.7$$
$$	ext{p}K_a(	ext{HCN}) = 9.3$$
$$	ext{p}K_a(	ext{CH}_3	ext{CO}_2	ext{H}) = 4.76$$
$$	ext{p}K_a(	ext{HNO}_3) = -1.3$$

Accepted Answer

$$	ext{HNO}_3$$

Question 8

Predict whether the following acid-base reaction will proceed to the right to a significant extent:

$$	ext{HCN} + 	ext{CH}_3	ext{CO}_2^- ightarrow 	ext{CN}^- + 	ext{CH}_3	ext{CO}_2	ext{H}$$

Given $$	ext{p}K_a(	ext{HCN}) = 9.3$$, $$	ext{p}K_a(	ext{CH}_3	ext{CO}_2	ext{H}) = 4.76$$

Accepted Answer

No, because acetic acid is a stronger acid than HCN.

Question 9

Which of the following best describes a Lewis acid?

Accepted Answer

A substance that accepts an electron pair.

Question 10

Which of the following molecules can act as both a Brønsted-Lowry acid and a Brønsted-Lowry base?

Accepted Answer

$$	ext{H}_2	ext{O}$$

Question 11

Which type of noncovalent interaction is primarily responsible for the double-helix structure of DNA?

Accepted Answer

Hydrogen bonding

Question 12

Which of the following compounds is most likely to be soluble in water, and why?

Accepted Answer

Vitamin C, because it has several $$-	ext{OH}$$ groups that can form hydrogen bonds with water.

Question 13

Which of the following best explains why benzene ($$	ext{C}_6	ext{H}_6) $$has zero dipole moment?

Accepted Answer

The molecule is highly symmetrical, causing individual bond dipoles to cancel.

Question 14

Which of the following is a correct application of the inductive effect?

Accepted Answer

Electronegative atoms withdraw electron density through sigma bonds, stabilizing negative charges nearby.

Question 15

Which of the following best describes the movement of electrons in resonance structures?

Accepted Answer

Only pi electrons and lone pairs move; sigma bonds remain unchanged.

Question 16

Which of the following is a Lewis base?

Accepted Answer

$$	ext{CH}_3	ext{NH}_2$$

Question 17

Which of the following best explains why methanol ($$	ext{CH}_3	ext{OH}) $$has a dipole moment of 1.70 D?

Accepted Answer

The O–H and C–O bonds are both polar, and their dipoles do not cancel due to the molecule's geometry.

Question 18

Which of the following best describes the relationship between acid strength and pKa?

Accepted Answer

Stronger acids have lower pKa values.

Question 19

Which of the following is the best example of a molecule stabilized by resonance?

Accepted Answer

Acetate ion ($$	ext{CH}_3	ext{CO}_2^-)$$

Polar Covalent Bonds, Acids, and Bases: Foundations of Organic Chemistry

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