Question 1

Which type of bond is responsible for holding the hydrogen and oxygen atoms together within a single water molecule, as shown in the first image?

Accepted Answer

Polar covalent bond

Question 2

What causes the partial negative charge ($$\delta^-) on $$the oxygen atom in a water molecule?

Accepted Answer

Oxygen has more protons than hydrogen, attracting electrons more strongly

Question 3

In the second image, what type of bond is depicted as a dashed line between two water molecules?

Accepted Answer

Hydrogen bond

Question 4

Why does ice float on liquid water, based on the molecular structure of water?

Accepted Answer

Hydrogen bonds in ice form a crystalline lattice that spaces molecules farther apart

Question 5

Which property of water allows it to dissolve ionic compounds like salt?

Accepted Answer

Its ability to form hydrogen bonds with ions

Question 6

A drought-resistant tree is hypothesized to have narrow xylem vessels. What is the main advantage of this adaptation?

Accepted Answer

It maintains cohesive water columns under high tension

Question 7

Which of the following best explains why water is called the 'universal solvent'?

Accepted Answer

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

Question 8

If you add a strong base to distilled water, what will happen to the pH compared to adding the same base to a phosphate buffer?

Accepted Answer

The pH of distilled water will increase much more rapidly

Question 9

Which scenario best illustrates the 'like dissolves like' principle?

Accepted Answer

Salt dissolving in water, but not in hexane

Question 10

A lake in winter has ice on the surface, cold water just below, and the densest water at the bottom. Which temperature is found at the bottom layer?

Accepted Answer

$$4^\circ C$$

Question 11

Which adaptation would most likely help a plant reduce water loss in a dry, windy environment?

Accepted Answer

Sunken stomata and thick waxy cuticle

Question 12

What is the main reason aquatic organisms can survive in lakes during winter?

Accepted Answer

Ice floats, insulating the warmer, denser water below

Question 13

Which of the following best describes the effect of increasing air movement on transpiration in plants?

Accepted Answer

It increases the rate of transpiration under both humid and dry conditions

Question 14

Which of the following substances would NOT dissolve well in water?

Accepted Answer

Vegetable oil

Question 15

Which equation best represents the relationship between pH and hydrogen ion concentration $$[H^+]$$?

Accepted Answer

$$pH = -\log_{10} [H^+]$$

Question 16

Which property of water is most directly responsible for the upward movement of water in plant xylem?

Accepted Answer

Cohesion due to hydrogen bonding

Question 17

Why does water have a bent molecular shape rather than a linear one?

Accepted Answer

The lone pairs of electrons on oxygen repel the hydrogen atoms

Question 18

Which of the following best explains why a phosphate buffer resists changes in pH when a base is added?

Accepted Answer

Its weak acid/base components neutralize added base ions

Question 19

Which of the following is a direct consequence of water's polarity?

Accepted Answer

Water molecules form hydrogen bonds with each other

Question 20

A student adds sugar to both water and hexane. What is the expected result and why?

Accepted Answer

Sugar dissolves in water due to hydrogen bonding, but not in hexane

Water and Life: Structure, Properties, and Biological Importance

Study Guide - Practice Questions