$$[H^+] = 1 \times 10$$^{-4}$$ M

Question 1

Which property of water allows a spider to walk on the surface of a pond without sinking?

Accepted Answer

Cohesive behavior due to hydrogen bonding

Question 2

Why does ice float on liquid water, and why is this important for aquatic life?

Accepted Answer

Ice is less dense than liquid water due to hydrogen bonds forming an open lattice, which insulates aquatic life below.

Question 3

Which of the following best explains why coastal areas tend to have milder climates than inland areas?

Accepted Answer

Water has a high specific heat, absorbing and releasing heat slowly, moderating temperature changes.

Question 4

A solution has a pH of 4. What is the concentration of hydrogen ions $$[H^+] in $$this solution?

Accepted Answer

$$[H^+] = 1 	imes 10$$^{-4}$$ M

Question 5

Which of the following scenarios demonstrates evaporative cooling?

Accepted Answer

Sweat evaporating from human skin, lowering body temperature.

Question 6

What type of bond forms between the oxygen atom of one water molecule and the hydrogen atom of another water molecule?

Accepted Answer

Hydrogen bond

Question 7

Which of the following best describes why water is an excellent solvent for ionic compounds like NaCl?

Accepted Answer

Water molecules are polar and form hydration shells around ions, separating them.

Question 8

If a solution has a pH of 9, which of the following statements is true?

Accepted Answer

The solution is basic and has a low $$[H^+]$$ concentration.

Question 9

Which equation correctly represents the dissociation of water molecules?

Accepted Answer

$$2H_2O \rightleftharpoons H_3O^+ + OH^-$$

Question 10

Which property of water is most directly responsible for the transport of water from roots to leaves in plants?

Accepted Answer

Cohesion and adhesion due to hydrogen bonding

Question 11

Ocean acidification is primarily caused by which chemical reaction?

Accepted Answer

$$CO_2$$ dissolving in seawater to form $$H_2CO_3 ($$carbonic acid), which lowers ocean pH.

Question 12

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

Accepted Answer

Sweat absorbs heat as it evaporates, removing energy from the body.

Question 13

A hydrophobic substance will:

Accepted Answer

Not dissolve in water

Question 14

Which of the following is a direct consequence of water’s high heat of vaporization?

Accepted Answer

Evaporation of water cools surfaces, such as animal skin.

Question 15

Which of the following statements about acids and bases is correct?

Accepted Answer

Acids increase the $$[H^+]$$ concentration, while bases decrease it.

Question 16

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

Accepted Answer

The oxygen atom is partially negative, and the hydrogen atoms are partially positive.

Question 17

If the pH of a solution changes from 6 to 4, how does the $$[H^+]$$ concentration change?

Accepted Answer

It increases by 100 times.

Question 18

Which property of water helps maintain a stable temperature in oceans, supporting marine life?

Accepted Answer

High specific heat

Question 19

Which of the following is an example of water acting as a solvent in a biological system?

Accepted Answer

Salt (NaCl) dissolving in blood plasma

Question 20

Which of the following best explains why water molecules can form hydrogen bonds with each other?

Accepted Answer

Water molecules have polar covalent bonds, creating partial charges.

Water and Life: Properties, Structure, and Biological Importance

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