$$(6 \times 12) + (12 \times 1) + (6 \times 16) = 180$$

Question 1

Which property of water is primarily responsible for the ability of some insects, such as water striders, to walk on the surface of a pond?

Accepted Answer

Surface tension due to hydrogen bonding

Question 2

A scientist adds 0.01 moles of hydrochloric acid (HCl) to 1 liter of pure water. What is the resulting pH of the solution? Use $$pH = -\log [H^+].$$

Accepted Answer

$$pH = -\log[0.01] = 2$$

Question 3

Why does ice float on liquid water?

Accepted Answer

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

Question 4

Which of the following best explains why water has a high specific heat compared to other substances?

Accepted Answer

Hydrogen bonds between water molecules require more energy to break

Question 5

A solution has a hydrogen ion concentration of $$[H^+] = 1 	imes 10$$^{-5}$$ M. What is its pH?

Accepted Answer

$$pH = 5$$

Question 6

Which of the following is NOT a consequence of water’s polarity?

Accepted Answer

Water can dissolve nonpolar substances easily

Question 7

If a lake were to freeze from the bottom up instead of the top down, which property of water would be most directly responsible for the change?

Accepted Answer

Water’s density increases as it freezes

Question 8

Which of the following best describes the relationship between heat and temperature?

Accepted Answer

Heat is the total kinetic energy of molecules; temperature is the average kinetic energy

Question 9

A buffer is added to a solution to minimize pH changes. Which of the following best describes how a buffer works?

Accepted Answer

It removes or adds $$H^+$$ ions to maintain a stable pH

Question 10

Which of the following is an example of adhesion?

Accepted Answer

Water molecules clinging to the walls of a plant’s xylem vessels

Question 11

Calculate the molecular mass of glucose ($$C_6H_{12}O_6$) given: C = 12, H = 1, O = 16.

Accepted Answer

$$(6 	imes 12) + (12 	imes 1) + (6 	imes 16) = 180$$

Question 12

Which of the following statements about hydrophobic substances is correct?

Accepted Answer

They are nonpolar and do not dissolve in water

Question 13

What is the molarity of a solution containing 0.5 moles of NaCl dissolved in 2 liters of water?

Accepted Answer

$$M = \frac{0.5}{2} = 0.25 M$$

Question 14

Which of the following best explains why water is considered the 'solvent of life'?

Accepted Answer

Water’s polarity allows it to dissolve many ionic and polar substances

Question 15

Which of the following is a direct effect of ocean acidification on marine organisms?

Accepted Answer

Decreased availability of carbonate ions, making calcification more difficult

Question 16

Which of the following is true about isomers?

Accepted Answer

Isomers have the same molecular formula but different structures

Question 17

Which functional group is most likely to act as an acid in aqueous solution?

Accepted Answer

Carboxyl group ($$-COOH)$$

Question 18

Which of the following best describes the process of evaporative cooling?

Accepted Answer

As water evaporates, the surface temperature decreases due to loss of high-energy molecules

Question 19

Which of the following is a real-world example of water’s cohesion?

Accepted Answer

Water droplets forming beads on a waxed car hood

Question 20

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds result from atoms sharing electrons

Properties of Water, Chemical Bonds, and pH in Biology

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