Q: A sample of water is heated from 20°C to 80°C. If the mass of water is 100 g, how much energy is required? (Specific heat capacity of water $$c = 4.18 \ \mathrm{J} \cdot \mathrm{g}^{-1} \cdot \mathrm{K}^{-1})$$

$$Q = 100 \times 4.18 \times (80-20) = 25,080 \ \mathrm{J}$$

Question 1

Which property of water allows it to act as an effective solvent for ionic compounds such as NaCl?

Accepted Answer

Its polarity and ability to form hydrogen bonds

Question 2

Why does ice float on liquid water, and what is the biological significance of this property?

Accepted Answer

Ice is less dense than water due to hydrogen bonding, insulating aquatic habitats during winter.

Question 3

Which equation correctly describes the relationship between heat energy, mass, specific heat capacity, and temperature change in water?

Accepted Answer

$$Q = mc\Delta T$$

Question 4

A plant draws water up through its xylem vessels. Which combination of water’s properties is primarily responsible for this process?

Accepted Answer

Cohesion and adhesion

Question 5

Which of the following best explains why sweating cools the human body?

Accepted Answer

Evaporation of water requires breaking hydrogen bonds, absorbing heat from the skin.

Question 6

Which of the following molecules would be LEAST soluble in blood plasma?

Accepted Answer

Cholesterol

Question 7

Why do aquatic animals require less energy to float compared to terrestrial animals?

Accepted Answer

The density of water is closer to that of living organisms, increasing buoyancy.

Question 8

Which property of water is most responsible for the formation of a meniscus in a glass tube?

Accepted Answer

Adhesion

Question 9

A scientist observes that water droplets form beads on a spider web. Which property of water is primarily responsible for this phenomenon?

Accepted Answer

Cohesion between water molecules

Question 10

Which of the following best describes why enzymes require water to function properly in cells?

Accepted Answer

Hydrogen bonds between water and enzyme binding sites facilitate substrate interactions.

Question 11

Which of the following statements about the phospholipid bilayer is correct?

Accepted Answer

The hydrophilic heads interact with water, while the hydrophobic tails are shielded from water.

Question 12

Which property of water allows it to moderate Earth's climate and stabilize aquatic environments?

Accepted Answer

High specific heat capacity

Question 13

A sample of water is heated from 20°C to 80°C. If the mass of water is 100 g, how much energy is required? (Specific heat capacity of water $$c = 4.18 \ \mathrm{J} \cdot \mathrm{g}^{-1} \cdot \mathrm{K}^{-1})$$

Accepted Answer

$$Q = 100 	imes 4.18 	imes (80-20) = 25,080 \ \mathrm{J}$$

Question 14

Which of the following best explains why oil and water do not mix?

Accepted Answer

Oil is nonpolar and hydrophobic, while water is polar and hydrophilic.

Question 15

Which adaptation helps marine mammals like seals minimize heat loss in cold water?

Accepted Answer

A thick layer of blubber acting as insulation

Question 16

Which of the following is a consequence of water’s high thermal conductivity for aquatic animals?

Accepted Answer

They lose heat to the environment quickly.

Question 17

Which of the following best describes the difference between cohesion and adhesion?

Accepted Answer

Cohesion is the attraction between water molecules; adhesion is the attraction between water and other substances.

Question 18

Which property of water is most important for the transport of nutrients and waste in blood plasma?

Accepted Answer

Excellent solvent properties

Question 19

Why do plants require both cohesion and adhesion for water transport from roots to leaves?

Accepted Answer

Cohesion keeps water molecules together, while adhesion helps water stick to cell walls and move upward.

Question 20

Which of the following best explains why aquatic environments are more thermally stable than terrestrial environments?

Accepted Answer

Water has a high specific heat capacity, so it resists temperature changes.

Water: Physical and Chemical Properties Essential for Life

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