Question 1

Which property of water is primarily responsible for the ability of some insects to walk on water surfaces?

Accepted Answer

Surface tension due to hydrogen bonding

Question 2

Why does ice float on liquid water, and what would be the consequence if it did not?

Accepted Answer

Ice is less dense than liquid water because hydrogen bonds are more ordered; if it sank, all bodies of water would freeze solid.

Question 3

A scientist dissolves table salt (NaCl) in water. What property of water allows this to happen, and what forms around the ions?

Accepted Answer

Water's polarity; a hydration shell forms around the ions

Question 4

Which equation correctly represents the relationship between hydrogen ion and hydroxide ion concentrations in pure water at 25°C?

Accepted Answer

$$[H^+][OH^-] = 10$$^{-14}$$

Question 5

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

Accepted Answer

Water has a high specific heat, allowing it to absorb and release large amounts of heat with little temperature change.

Question 6

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

Accepted Answer

$$pH = 5$$

Question 7

Which of the following is NOT one of the four emergent properties of water that contribute to Earth's suitability for life?

Accepted Answer

High viscosity

Question 8

What is the main reason water is considered the 'solvent of life'?

Accepted Answer

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

Question 9

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

Accepted Answer

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

Question 10

A buffer solution contains a weak acid and its corresponding base. What is the primary function of a buffer in biological systems?

Accepted Answer

To minimize changes in concentrations of $$H^+$$ and $$OH^-$$ ions

Question 11

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

Accepted Answer

An acid is a substance that increases the $$H^+$$ concentration of a solution.

Question 12

What is the effect of ocean acidification on marine organisms such as corals?

Accepted Answer

It decreases the availability of carbonate ions, hindering calcification.

Question 13

Which of the following best explains why water has a high specific heat?

Accepted Answer

Hydrogen bonds between water molecules absorb heat when they break and release heat when they form.

Question 14

A biologist is searching for life on another planet. Why is the presence of water considered a key factor in this search?

Accepted Answer

Water's unique properties support the chemical reactions necessary for life.

Question 15

Which of the following best describes a hydrophobic substance?

Accepted Answer

A substance that does not have an affinity for water

Question 16

If the concentration of $$OH^- in a $$solution is $$10^{-9} M$$, what is the concentration of $$H^+ at 25$$°C?

Accepted Answer

$$10^{-5} M$\ (	ext{since}\ [H^+][OH^-] = 10$$^{-14}$$)$$

Question 17

Which of the following is an example of water's adhesive property in nature?

Accepted Answer

Water molecules clinging to plant cell walls, aiding in water transport

Question 18

What is the main effect of adding a strong acid to pure water?

Accepted Answer

It increases the $$H^+$$ concentration

Question 19

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

Accepted Answer

As water evaporates, the surface that remains cools down because the molecules with the highest kinetic energy leave first.

Question 20

Which of the following is true about the dissociation of water molecules?

Accepted Answer

It is statistically rare but has a great effect on organisms.

Water and Life: Properties, Structure, and Biological Importance

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