Question 1

Which property of water is primarily responsible for its ability to dissolve ionic compounds such as NaCl?

Accepted Answer

High dielectric constant

Question 2

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Ice forms a crystalline lattice that is less dense than liquid water.

Question 3

A water molecule can form up to how many hydrogen bonds with neighboring water molecules?

Accepted Answer

$$4$$

Question 4

Which of the following statements about hydrogen bonds in biological molecules is CORRECT?

Accepted Answer

Hydrogen bonds can form between water and functional groups such as alcohols and amines.

Question 5

Given the following bond energies, which interaction is the weakest?

$$	ext{Covalent bond: } \u003e 300\ 	ext{kJ/mol}$$
$$	ext{Ionic interaction: } 86\ 	ext{kJ/mol}$$
$$	ext{Hydrogen bond: } 20\ 	ext{kJ/mol}$$
$$	ext{van der Waals: } 0.3\ 	ext{kJ/mol}$$

Accepted Answer

van der Waals

Question 6

Which of the following best describes the hydrophobic effect?

Accepted Answer

The exclusion of nonpolar substances from water, increasing entropy of water.

Question 7

Which of the following is a consequence of water’s high heat capacity for living organisms?

Accepted Answer

Water helps buffer organisms against sudden temperature changes.

Question 8

Which of the following functional groups can act as a hydrogen bond acceptor in biological molecules?

Accepted Answer

Carboxylate group ($$-COO^-)$$

Question 9

Why do amphipathic molecules such as phospholipids form bilayers in aqueous solutions?

Accepted Answer

Their polar heads interact with water while nonpolar tails aggregate to minimize contact with water.

Question 10

Which of the following best explains why water has a higher boiling point than methane ($$CH_4) $$despite similar molecular weights?

Accepted Answer

Water forms extensive hydrogen bonds.

Question 11

A protein’s tertiary structure is stabilized by multiple noncovalent interactions. Which of the following is NOT a noncovalent interaction?

Accepted Answer

Disulfide bond

Question 12

Which of the following best describes the geometry of a water molecule?

Accepted Answer

Tetrahedral, with a bond angle of $$104.5^\circ$$

Question 13

Which of the following statements about van der Waals interactions is TRUE?

Accepted Answer

They arise from transient dipoles in nonpolar molecules.

Question 14

Which of the following is a real-life example of the hydrophobic effect?

Accepted Answer

Oil droplets aggregating in water

Question 15

Which property of water allows insects such as water striders to walk on its surface?

Accepted Answer

High surface tension

Question 16

Which of the following best describes a hydrogen bond donor?

Accepted Answer

A hydrogen atom covalently bonded to an electronegative atom

Question 17

Which of the following is the main reason why water is an excellent solvent for polar and ionic substances?

Accepted Answer

Water has a high dielectric constant and forms hydrogen bonds with solutes.

Question 18

Which of the following best explains why the interior of a biological membrane is hydrophobic?

Accepted Answer

It is composed of fatty acid tails that avoid water.

Question 19

Which of the following is a correct statement about the concentration of water in pure water at room temperature?

Accepted Answer

$$55.5\ 	ext{M}$$

Question 20

Which of the following is a direct consequence of the tetrahedral geometry of water?

Accepted Answer

Water can form up to four hydrogen bonds.

Aqueous Chemistry: Water and Noncovalent Interactions in Biochemistry

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